Prakitr Srisuma, George Barbastathis, Richard D. Braatz
Lyophilization (also known as freeze drying) is a process that is commonly used to increase the stability of drug products, e.g., mRNA vaccines, in pharmaceutical manufacturing. While extensive efforts have been dedicated to shift the pharmaceutical industry towards continuous manufacturing, the majority of industrial-scale lyophilization is still being operated in a batch mode. This article proposes the first mechanistic model for a complete continuous lyophilization process, which includes freezing, primary drying, and secondary drying. The state-of-the-art lyophilization technology is considered, in which vials are suspended and moved continuously through the process. The model can describe the evolution of several critical process parameters, namely the product temperature, ice/water fraction, sublimation front position, and concentration of bound water, for the entire lyophilization process. The model is also demonstrated for several applications related to process design and optimization. Ultimately, the framework and results presented in this work can serve as a solid foundation to guide the design and development of future continuous lyophilization processes.
{"title":"Mechanistic Modeling of Continuous Lyophilization for Pharmaceutical Manufacturing","authors":"Prakitr Srisuma, George Barbastathis, Richard D. Braatz","doi":"arxiv-2409.06251","DOIUrl":"https://doi.org/arxiv-2409.06251","url":null,"abstract":"Lyophilization (also known as freeze drying) is a process that is commonly\u0000used to increase the stability of drug products, e.g., mRNA vaccines, in\u0000pharmaceutical manufacturing. While extensive efforts have been dedicated to\u0000shift the pharmaceutical industry towards continuous manufacturing, the\u0000majority of industrial-scale lyophilization is still being operated in a batch\u0000mode. This article proposes the first mechanistic model for a complete\u0000continuous lyophilization process, which includes freezing, primary drying, and\u0000secondary drying. The state-of-the-art lyophilization technology is considered,\u0000in which vials are suspended and moved continuously through the process. The\u0000model can describe the evolution of several critical process parameters, namely\u0000the product temperature, ice/water fraction, sublimation front position, and\u0000concentration of bound water, for the entire lyophilization process. The model\u0000is also demonstrated for several applications related to process design and\u0000optimization. Ultimately, the framework and results presented in this work can\u0000serve as a solid foundation to guide the design and development of future\u0000continuous lyophilization processes.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Understanding the behavior of complex molecular systems is a fundamental problem in physical chemistry. To describe the long-time dynamics of such systems, which is responsible for their most informative characteristics, we can identify a few slow collective variables (CVs) while treating the remaining fast variables as thermal noise. This enables us to simplify the dynamics and treat it as diffusion in a free-energy landscape spanned by slow CVs, effectively rendering the dynamics Markovian. Our recent statistical learning technique, spectral map [Rydzewski, J. Phys. Chem. Lett. 2023, 14, 22, 5216-5220], explores this strategy to learn slow CVs by maximizing a spectral gap of a transition matrix. In this work, we introduce several advancements into our framework, using a high-dimensional reversible folding process of a protein as an example. We implement an algorithm for coarse-graining Markov transition matrices to partition the reduced space of slow CVs kinetically and use it to define a transition state ensemble. We show that slow CVs learned by spectral map closely approach the Markovian limit for an overdamped diffusion. We demonstrate that coordinate-dependent diffusion coefficients only slightly affect the constructed free-energy landscapes. Finally, we present how spectral map can be used to quantify the importance of features and compare slow CVs with structural descriptors commonly used in protein folding. Overall, we demonstrate that a single slow CV learned by spectral map can be used as a physical reaction coordinate to capture essential characteristics of protein folding.
{"title":"Spectral Map for Slow Collective Variables, Markovian Dynamics, and Transition State Ensembles","authors":"Jakub Rydzewski","doi":"arxiv-2409.06428","DOIUrl":"https://doi.org/arxiv-2409.06428","url":null,"abstract":"Understanding the behavior of complex molecular systems is a fundamental\u0000problem in physical chemistry. To describe the long-time dynamics of such\u0000systems, which is responsible for their most informative characteristics, we\u0000can identify a few slow collective variables (CVs) while treating the remaining\u0000fast variables as thermal noise. This enables us to simplify the dynamics and\u0000treat it as diffusion in a free-energy landscape spanned by slow CVs,\u0000effectively rendering the dynamics Markovian. Our recent statistical learning\u0000technique, spectral map [Rydzewski, J. Phys. Chem. Lett. 2023, 14, 22,\u00005216-5220], explores this strategy to learn slow CVs by maximizing a spectral\u0000gap of a transition matrix. In this work, we introduce several advancements\u0000into our framework, using a high-dimensional reversible folding process of a\u0000protein as an example. We implement an algorithm for coarse-graining Markov\u0000transition matrices to partition the reduced space of slow CVs kinetically and\u0000use it to define a transition state ensemble. We show that slow CVs learned by\u0000spectral map closely approach the Markovian limit for an overdamped diffusion.\u0000We demonstrate that coordinate-dependent diffusion coefficients only slightly\u0000affect the constructed free-energy landscapes. Finally, we present how spectral\u0000map can be used to quantify the importance of features and compare slow CVs\u0000with structural descriptors commonly used in protein folding. Overall, we\u0000demonstrate that a single slow CV learned by spectral map can be used as a\u0000physical reaction coordinate to capture essential characteristics of protein\u0000folding.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Daniel Lozano-Martín, Salomé Inês Cardoso Vieira, Xavier Paredes, Maria José Vitoriano Lourenço, Carlos A. Nieto de Castro, Jan V. Sengers, Klemens Massonne
Ionic liquids have been suggested as new engineering fluids, namely in the area of heat transfer, as alternatives to current biphenyl and diphenyl oxide, alkylated aromatics and dimethyl polysiloxane oils, which degrade above 200 {deg}C and pose some environmental problems. Recently, we have proposed 1-ethyl-3-methylimidazolium methanesulfonate, [$C_{2}mim$][$CH_{3}SO_{3}$], as a new heat transfer fluid, because of its thermophysical and toxicological properties. However, there are some interesting points raised in this work, namely the possibility of the existence of liquid metastability below the melting point (303 K) or second order-disorder transitions ($lambda$-type) before reaching the calorimetric freezing point. This paper analyses in more detail this zone of the phase diagram of the pure fluid, by reporting accurate thermal-conductivity measurements between 278 and 355 K with an estimated uncertainty of 2% at a 95% confidence level. A new value of the melting temperature is also reported, $T_{melt}$ = 307.8 $pm$ 1 K. Results obtained support liquid metastability behaviour in the solid-phase region and permit the use of this ionic liquid at a heat transfer fluid at temperatures below its melting point. Thermal conductivity models based on Bridgman theory and estimation formulas were also used in this work, failing to predict the experimental data within its uncertainty.
{"title":"Thermal Conductivity of Metastable Ionic Liquid [$C_{2}mim$][$CH_{3}SO_{3}$]","authors":"Daniel Lozano-Martín, Salomé Inês Cardoso Vieira, Xavier Paredes, Maria José Vitoriano Lourenço, Carlos A. Nieto de Castro, Jan V. Sengers, Klemens Massonne","doi":"arxiv-2409.06346","DOIUrl":"https://doi.org/arxiv-2409.06346","url":null,"abstract":"Ionic liquids have been suggested as new engineering fluids, namely in the\u0000area of heat transfer, as alternatives to current biphenyl and diphenyl oxide,\u0000alkylated aromatics and dimethyl polysiloxane oils, which degrade above 200\u0000{deg}C and pose some environmental problems. Recently, we have proposed\u00001-ethyl-3-methylimidazolium methanesulfonate, [$C_{2}mim$][$CH_{3}SO_{3}$], as\u0000a new heat transfer fluid, because of its thermophysical and toxicological\u0000properties. However, there are some interesting points raised in this work,\u0000namely the possibility of the existence of liquid metastability below the\u0000melting point (303 K) or second order-disorder transitions ($lambda$-type)\u0000before reaching the calorimetric freezing point. This paper analyses in more\u0000detail this zone of the phase diagram of the pure fluid, by reporting accurate\u0000thermal-conductivity measurements between 278 and 355 K with an estimated\u0000uncertainty of 2% at a 95% confidence level. A new value of the melting\u0000temperature is also reported, $T_{melt}$ = 307.8 $pm$ 1 K. Results obtained\u0000support liquid metastability behaviour in the solid-phase region and permit the\u0000use of this ionic liquid at a heat transfer fluid at temperatures below its\u0000melting point. Thermal conductivity models based on Bridgman theory and\u0000estimation formulas were also used in this work, failing to predict the\u0000experimental data within its uncertainty.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190285","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Samuel P. Niblett, Panagiotis Kourtis, Ioan-Bogdan Magdău, Clare P. Grey, Gábor Csányi
With the emergence of Foundational Machine Learning Interatomic Potential (FMLIP) models trained on extensive datasets, transferring data between different ML architectures has become increasingly important. In this work, we examine the extent to which training data optimised for one machine-learning forcefield algorithm may be re-used to train different models, aiming to accelerate FMLIP fine-tuning and to reduce the need for costly iterative training. As a test case, we train models of an organic liquid mixture that is commonly used as a solvent in rechargeable battery electrolytes, making it an important target for reactive MLIP development. We assess model performance by analysing the properties of molecular dynamics trajectories, showing that this is a more stringent test than comparing prediction errors for fixed datasets. We consider several types of training data, and several popular MLIPs - notably the recent MACE architecture, a message-passing neural network designed for high efficiency and smoothness. We demonstrate that simple training sets constructed without any ab initio dynamics are sufficient to produce stable models of molecular liquids. For simple neural-network architectures, further iterative training is required to capture thermodynamic and kinetic properties correctly, but MACE performs well with extremely limited datsets. We find that configurations designed by human intuition to correct systematic model deficiencies transfer effectively between algorithms, but active-learned data that are generated by one MLIP do not typically benefit a different algorithm. Finally, we show that any training data which improve model performance also improve its ability to generalise to similar unseen molecules. This suggests that trajectory failure modes are connected with chemical structure rather than being entirely system-specific.
{"title":"Transferability of datasets between Machine-Learning Interaction Potentials","authors":"Samuel P. Niblett, Panagiotis Kourtis, Ioan-Bogdan Magdău, Clare P. Grey, Gábor Csányi","doi":"arxiv-2409.05590","DOIUrl":"https://doi.org/arxiv-2409.05590","url":null,"abstract":"With the emergence of Foundational Machine Learning Interatomic Potential\u0000(FMLIP) models trained on extensive datasets, transferring data between\u0000different ML architectures has become increasingly important. In this work, we\u0000examine the extent to which training data optimised for one machine-learning\u0000forcefield algorithm may be re-used to train different models, aiming to\u0000accelerate FMLIP fine-tuning and to reduce the need for costly iterative\u0000training. As a test case, we train models of an organic liquid mixture that is\u0000commonly used as a solvent in rechargeable battery electrolytes, making it an\u0000important target for reactive MLIP development. We assess model performance by\u0000analysing the properties of molecular dynamics trajectories, showing that this\u0000is a more stringent test than comparing prediction errors for fixed datasets.\u0000We consider several types of training data, and several popular MLIPs - notably\u0000the recent MACE architecture, a message-passing neural network designed for\u0000high efficiency and smoothness. We demonstrate that simple training sets\u0000constructed without any ab initio dynamics are sufficient to produce stable\u0000models of molecular liquids. For simple neural-network architectures, further\u0000iterative training is required to capture thermodynamic and kinetic properties\u0000correctly, but MACE performs well with extremely limited datsets. We find that\u0000configurations designed by human intuition to correct systematic model\u0000deficiencies transfer effectively between algorithms, but active-learned data\u0000that are generated by one MLIP do not typically benefit a different algorithm.\u0000Finally, we show that any training data which improve model performance also\u0000improve its ability to generalise to similar unseen molecules. This suggests\u0000that trajectory failure modes are connected with chemical structure rather than\u0000being entirely system-specific.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Luis Felipe Sanz, Juan Antonio González, Fernando Hevia, Daniel Lozano-Martín, Isaías García de la Fuente, José Carlos Cobos
Kinematic viscosities were measured for iodobenzene + n-alkane mixtures at (288.15-308.15) K and atmospheric pressure. Using our previous density data, dynamic viscosities ($eta$), deviations in absolute viscosity ($Delta eta$) and quantities of viscous flow were determined. The McAllister, Grunberg-Nissan and Fang-He correlation equations and Bloomfield-Dewan's model (with residual Gibbs energies calculated using DISQUAC with interaction parameters available in the literature) were applied to iodobenzene, or 1-chloronaphthalene, or 1,2,4-trichlorobenzene, or methyl benzoate or benzene or cyclohexane + n-alkane systems. The dependence of $U_{text{m,}V}^{text{E}}$ (isochoric molar excess internal energy) and $Delta eta$ with $n$ (the number of C atoms of the n-alkane) shows that the fluidization loss of mixtures containing iodobenzene, 1,2,4-trichlorobenzene, or 1-chloronaphthalene when $n$ increases is due to a decrease upon mixing of the number of broken interactions between like molecules. The breaking of correlations of molecular orientations characteristic of longer n-alkanes may explain the decreased negative $Delta eta$ values of benzene mixtures with $n$ =14,16. The replacement, in this type of systems of benzene by cyclohexane leads to increased positive $Delta eta$ values, probably due to the different shape of cyclohexane. On the other hand, binary mixtures formed by one of the aromatic polar compounds mentioned above and a short n-alkane show large structural effects and large negative $Delta eta$ values. From the application of the models, it seems that dispersive interactions are dominant and that size effects are not relevant on $eta$ values. The free volume model provides good results for most of the systems considered. Results improve when, within Bloomfield-Dewan's theory, the contribution to $eta$ of the absolute reaction rate model is also considered.
{"title":"Viscosities of iodobenzene + n-alkane mixtures at (288.15-308.15) K. Measurements and results from models","authors":"Luis Felipe Sanz, Juan Antonio González, Fernando Hevia, Daniel Lozano-Martín, Isaías García de la Fuente, José Carlos Cobos","doi":"arxiv-2409.05426","DOIUrl":"https://doi.org/arxiv-2409.05426","url":null,"abstract":"Kinematic viscosities were measured for iodobenzene + n-alkane mixtures at\u0000(288.15-308.15) K and atmospheric pressure. Using our previous density data,\u0000dynamic viscosities ($eta$), deviations in absolute viscosity ($Delta eta$)\u0000and quantities of viscous flow were determined. The McAllister, Grunberg-Nissan\u0000and Fang-He correlation equations and Bloomfield-Dewan's model (with residual\u0000Gibbs energies calculated using DISQUAC with interaction parameters available\u0000in the literature) were applied to iodobenzene, or 1-chloronaphthalene, or\u00001,2,4-trichlorobenzene, or methyl benzoate or benzene or cyclohexane + n-alkane\u0000systems. The dependence of $U_{text{m,}V}^{text{E}}$ (isochoric molar excess\u0000internal energy) and $Delta eta$ with $n$ (the number of C atoms of the\u0000n-alkane) shows that the fluidization loss of mixtures containing iodobenzene,\u00001,2,4-trichlorobenzene, or 1-chloronaphthalene when $n$ increases is due to a\u0000decrease upon mixing of the number of broken interactions between like\u0000molecules. The breaking of correlations of molecular orientations\u0000characteristic of longer n-alkanes may explain the decreased negative $Delta\u0000eta$ values of benzene mixtures with $n$ =14,16. The replacement, in this type\u0000of systems of benzene by cyclohexane leads to increased positive $Delta eta$\u0000values, probably due to the different shape of cyclohexane. On the other hand,\u0000binary mixtures formed by one of the aromatic polar compounds mentioned above\u0000and a short n-alkane show large structural effects and large negative $Delta\u0000eta$ values. From the application of the models, it seems that dispersive\u0000interactions are dominant and that size effects are not relevant on $eta$\u0000values. The free volume model provides good results for most of the systems\u0000considered. Results improve when, within Bloomfield-Dewan's theory, the\u0000contribution to $eta$ of the absolute reaction rate model is also considered.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fernando Hevia, Daniel Lozano-Martín, Juan Antonio González, Luis Felipe Sanz, Isaías García de la Fuente, José Carlos Cobos
(Iodobenzene + n-alkane) liquid mixtures have been studied experimentally, in terms of densities and speeds of sound at a pressure $p$ = 0.1 MPa and in the temperature range $T$ = (288.15 to 308.15) K, and theoretically, by the application of the Prigogine-Flory-Patterson (PFP) model. The n-alkanes considered are n-heptane, n-decane, n-dodecane, and n-tetradecane. Excess molar volumes ($V_{text{m}}^{text{E}}$) and excess isentropic compressibilities ($kappa_S^{text{E}}$) have been calculated and correlated by Redlich-Kister polynomials. ${(partial{V_{text{m}}^{text{E}}}/partial T)}_p$ curves at the same (p,T) conditions have been obtained from correlated $V_{text{m}}^{text{E}}$ values. From these experimental results and the knowledge of the excess molar enthalpies and volumes of mixtures containing fluorobenzene, chlorobenzene or bromobenzene with n-alkanes, we have inferred: (i) the presence of structural effects, especially important for the n-heptane mixture and less relevant for volumetric properties as the length of the n-alkane increases; and (ii) that the interactional effects on $V_{text{m}}^{text{E}}$ do not vary appreciably with the length of the n-alkane, so the observed $V_{text{m}}^{text{E}}$ variation is fundamentally determined by the corresponding variation of the contribution from structural effects. The application of the PFP model supports this interpretation, providing free volume contributions to $V_{text{m}}^{text{E}}$ that vary parallelly to $V_{text{m}}^{text{E}}$ with the length of the n-alkane, and interactional contributions that rest approximately constant independently of the n-alkane size.
{"title":"Density and speed of sound of (iodobenzene + n-alkane) liquid mixtures at $T$ = (288.15 to 308.15) K. Application of the Prigogine-Flory-Patterson model","authors":"Fernando Hevia, Daniel Lozano-Martín, Juan Antonio González, Luis Felipe Sanz, Isaías García de la Fuente, José Carlos Cobos","doi":"arxiv-2409.05422","DOIUrl":"https://doi.org/arxiv-2409.05422","url":null,"abstract":"(Iodobenzene + n-alkane) liquid mixtures have been studied experimentally, in\u0000terms of densities and speeds of sound at a pressure $p$ = 0.1 MPa and in the\u0000temperature range $T$ = (288.15 to 308.15) K, and theoretically, by the\u0000application of the Prigogine-Flory-Patterson (PFP) model. The n-alkanes\u0000considered are n-heptane, n-decane, n-dodecane, and n-tetradecane. Excess molar\u0000volumes ($V_{text{m}}^{text{E}}$) and excess isentropic compressibilities\u0000($kappa_S^{text{E}}$) have been calculated and correlated by Redlich-Kister\u0000polynomials. ${(partial{V_{text{m}}^{text{E}}}/partial T)}_p$ curves at the\u0000same (p,T) conditions have been obtained from correlated\u0000$V_{text{m}}^{text{E}}$ values. From these experimental results and the\u0000knowledge of the excess molar enthalpies and volumes of mixtures containing\u0000fluorobenzene, chlorobenzene or bromobenzene with n-alkanes, we have inferred:\u0000(i) the presence of structural effects, especially important for the n-heptane\u0000mixture and less relevant for volumetric properties as the length of the\u0000n-alkane increases; and (ii) that the interactional effects on\u0000$V_{text{m}}^{text{E}}$ do not vary appreciably with the length of the\u0000n-alkane, so the observed $V_{text{m}}^{text{E}}$ variation is fundamentally\u0000determined by the corresponding variation of the contribution from structural\u0000effects. The application of the PFP model supports this interpretation,\u0000providing free volume contributions to $V_{text{m}}^{text{E}}$ that vary\u0000parallelly to $V_{text{m}}^{text{E}}$ with the length of the n-alkane, and\u0000interactional contributions that rest approximately constant independently of\u0000the n-alkane size.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Juan Antonio González, Fernando Hevia, Luis Felipe Sanz, Daniel Lozano-Martín, Isaías García de la Fuente
The mixtures 2-propanol or 2-butanol + n-alkanone, or + acetophenone or + linear monoether, or + cyclic ether, or + linear organic carbonate, or + propylene carbonate have been investigated using thermodynamic data, and in terms of the Flory theory, and the Kirkwood-Buff integrals. The data considered are: excess molar enthalpies ($H_{text{m}}^{text{E}}$), volumes, entropies, and the temperature dependence of $H_{text{m}}^{text{E}}$. The enthalpy of the 2-alkanol-solvent interactions have been determined, and the different contributions to $H_{text{m}}^{text{E}}$ are discussed. It is shown that $H_{text{m}}^{text{E}}$ values of the 2-alkanol (fixed) + n-alkanone, or + linear carbonate mixtures change in the same manner that for n-alkanone, or linear carbonate + n-alkane (fixed) systems. In contrast, $H_{text{m}}^{text{E}}$ values of 2-alkanol (fixed) + linear monoether or + n-alkane mixtures change similarly. This set of results suggests that solvent-solvent interactions are determinant in systems with n-alkanone or linear carbonate, while interactions between alcohol molecules are determinant in mixtures with linear monoethers. According to the Flory model, orientational effects in systems with a given 2-alkanol become weaker in the sequence: linear monoether > linear organic carbonate > n-alkanone, and are stronger in solutions with a cyclic monoether than in those with cyclic diethers, and in systems with acetophenone or propylene carbonate than in the mixtures with the corresponding linear solvents. Results obtained from the Kirkwood-Buff integrals are consistent with these findings. The application of Flory model reveals that orientational effects are similar in systems with 1- or 2-alkanols, with the exception of solutions with linear monoethers, where such effects are stronger in mixtures containing 1-alkanols.
{"title":"Thermodynamics of 2-alkanol + polar organic solvent mixtures. I. Systems with ketones, ethers or organic carbonates","authors":"Juan Antonio González, Fernando Hevia, Luis Felipe Sanz, Daniel Lozano-Martín, Isaías García de la Fuente","doi":"arxiv-2409.05415","DOIUrl":"https://doi.org/arxiv-2409.05415","url":null,"abstract":"The mixtures 2-propanol or 2-butanol + n-alkanone, or + acetophenone or +\u0000linear monoether, or + cyclic ether, or + linear organic carbonate, or +\u0000propylene carbonate have been investigated using thermodynamic data, and in\u0000terms of the Flory theory, and the Kirkwood-Buff integrals. The data considered\u0000are: excess molar enthalpies ($H_{text{m}}^{text{E}}$), volumes, entropies,\u0000and the temperature dependence of $H_{text{m}}^{text{E}}$. The enthalpy of\u0000the 2-alkanol-solvent interactions have been determined, and the different\u0000contributions to $H_{text{m}}^{text{E}}$ are discussed. It is shown that\u0000$H_{text{m}}^{text{E}}$ values of the 2-alkanol (fixed) + n-alkanone, or +\u0000linear carbonate mixtures change in the same manner that for n-alkanone, or\u0000linear carbonate + n-alkane (fixed) systems. In contrast,\u0000$H_{text{m}}^{text{E}}$ values of 2-alkanol (fixed) + linear monoether or +\u0000n-alkane mixtures change similarly. This set of results suggests that\u0000solvent-solvent interactions are determinant in systems with n-alkanone or\u0000linear carbonate, while interactions between alcohol molecules are determinant\u0000in mixtures with linear monoethers. According to the Flory model, orientational\u0000effects in systems with a given 2-alkanol become weaker in the sequence: linear\u0000monoether > linear organic carbonate > n-alkanone, and are stronger in\u0000solutions with a cyclic monoether than in those with cyclic diethers, and in\u0000systems with acetophenone or propylene carbonate than in the mixtures with the\u0000corresponding linear solvents. Results obtained from the Kirkwood-Buff\u0000integrals are consistent with these findings. The application of Flory model\u0000reveals that orientational effects are similar in systems with 1- or\u00002-alkanols, with the exception of solutions with linear monoethers, where such\u0000effects are stronger in mixtures containing 1-alkanols.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Frederik Kamper Jørgensen, Erik Rosendahl Kjellgren, Hans Jørgen Aagaard Jensen, Erik Donovan Hedegård
We present the theory and implementation of a novel, fully variational wave function - density functional theory (DFT) hybrid model, which is applicable to many cases of strong correlation. We denote this model the multiconfigurational self-consistent on-top pair-density functional theory model (MC-srPDFT). We have previously shown how the multi-configurational short-range DFT hybrid model (MC-srDFT) can describe many multiconfigurational cases of any spin symmetry, and also state-specific calculations on excited states. However, the srDFT part of the MC-srDFT has some deficiencies that it shares with Kohn-Sham DFT, namely that different MS states have different energies and wrong bond dissociation description of singlet and non-singlet equilibrium states to open-shell fragments. The model we present in this paper corrects these deficiencies by introducing the on-top pair density. Unlike other models in the literature, our model is fully variational and employs a long-range version of the on-top pair density. The implementation is a second-order optimization algorithm ensuring robust convergence to both ground- and excited states. We show how MC-srPDFT solves the mentioned challenges by sample calculations on the ground state singlet curve of H$_2$, N$_2$, and Cr$_2$ and the lowest triplet curves for N$_2$ and Cr$_2$. The calculations show correct degeneracy between the singlet and triplet curves at dissociation and the results are invariant to the choice of MS value for the triplet curves.
{"title":"Multiconfigurational short-range on-top pair-density functional theory","authors":"Frederik Kamper Jørgensen, Erik Rosendahl Kjellgren, Hans Jørgen Aagaard Jensen, Erik Donovan Hedegård","doi":"arxiv-2409.05213","DOIUrl":"https://doi.org/arxiv-2409.05213","url":null,"abstract":"We present the theory and implementation of a novel, fully variational wave\u0000function - density functional theory (DFT) hybrid model, which is applicable to\u0000many cases of strong correlation. We denote this model the multiconfigurational\u0000self-consistent on-top pair-density functional theory model (MC-srPDFT). We\u0000have previously shown how the multi-configurational short-range DFT hybrid\u0000model (MC-srDFT) can describe many multiconfigurational cases of any spin\u0000symmetry, and also state-specific calculations on excited states. However, the\u0000srDFT part of the MC-srDFT has some deficiencies that it shares with Kohn-Sham\u0000DFT, namely that different MS states have different energies and wrong bond\u0000dissociation description of singlet and non-singlet equilibrium states to\u0000open-shell fragments. The model we present in this paper corrects these\u0000deficiencies by introducing the on-top pair density. Unlike other models in the\u0000literature, our model is fully variational and employs a long-range version of\u0000the on-top pair density. The implementation is a second-order optimization\u0000algorithm ensuring robust convergence to both ground- and excited states. We\u0000show how MC-srPDFT solves the mentioned challenges by sample calculations on\u0000the ground state singlet curve of H$_2$, N$_2$, and Cr$_2$ and the lowest\u0000triplet curves for N$_2$ and Cr$_2$. The calculations show correct degeneracy\u0000between the singlet and triplet curves at dissociation and the results are\u0000invariant to the choice of MS value for the triplet curves.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mohammed Loukili, Ludovic Jullien, Guillaume Baffou, Raphaël Plasson
Temperature gradients represent energy sources that can be harvested to generate steady reaction or transport fluxes. Technological developments could lead to the transfer of free energy from heat sources and sinks to chemical systems for the purpose of extraction, thermal batteries, or nonequilibrium synthesis. We present a theoretical study of 1D chemical systems subjected to temperature gradients. A complete theoretical framework describes the system behavior induced by various temperature profiles. An exact mathematical derivation was established for a simple two-compartment model, and generalized to arbitrary reaction-diffusion systems based on numerical models. An experimental system was eventually scaled and tuned to optimize either nonequilibrium chemical transport or reaction. The relevant parameters for this description were identified; they focused on the system symmetry for chemical reaction and transport. Nonequilibrium thermodynamic approaches lead to a description analogous to electric circuits. Temperature gradients lead to the onset of a steady chemical force, sustaining steady reaction-diffusion fluxes moderated by chemical resistance. The system activity was then assessed using the entropy production rate, as a measure of its dissipated power. The chemical characteristics of the system can be tuned for the general optimization of the nonequilibrium state or for the specific optimization of either transport or reaction processes. The temperature gradient shape can be tailored to precisely control the spatial localization of active processes, targeting either precise spatial localization or propagation over large areas. The resulting temperature-driven chemical system can in turn be used to drive secondary processes into either nonequilibrium reaction fluxes or concentration gradients.
{"title":"Optimizing reaction and transport fluxes in temperature gradient-driven chemical reaction-diffusion systems","authors":"Mohammed Loukili, Ludovic Jullien, Guillaume Baffou, Raphaël Plasson","doi":"arxiv-2409.04773","DOIUrl":"https://doi.org/arxiv-2409.04773","url":null,"abstract":"Temperature gradients represent energy sources that can be harvested to\u0000generate steady reaction or transport fluxes. Technological developments could\u0000lead to the transfer of free energy from heat sources and sinks to chemical\u0000systems for the purpose of extraction, thermal batteries, or nonequilibrium\u0000synthesis. We present a theoretical study of 1D chemical systems subjected to\u0000temperature gradients. A complete theoretical framework describes the system\u0000behavior induced by various temperature profiles. An exact mathematical\u0000derivation was established for a simple two-compartment model, and generalized\u0000to arbitrary reaction-diffusion systems based on numerical models. An\u0000experimental system was eventually scaled and tuned to optimize either\u0000nonequilibrium chemical transport or reaction. The relevant parameters for this description were identified; they focused on\u0000the system symmetry for chemical reaction and transport. Nonequilibrium\u0000thermodynamic approaches lead to a description analogous to electric circuits.\u0000Temperature gradients lead to the onset of a steady chemical force, sustaining\u0000steady reaction-diffusion fluxes moderated by chemical resistance. The system\u0000activity was then assessed using the entropy production rate, as a measure of\u0000its dissipated power. The chemical characteristics of the system can be tuned for the general\u0000optimization of the nonequilibrium state or for the specific optimization of\u0000either transport or reaction processes. The temperature gradient shape can be\u0000tailored to precisely control the spatial localization of active processes,\u0000targeting either precise spatial localization or propagation over large areas.\u0000The resulting temperature-driven chemical system can in turn be used to drive\u0000secondary processes into either nonequilibrium reaction fluxes or concentration\u0000gradients.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Despite the fact that most quantum chemistry basis sets are designed for accurately modelling valence chemistry, these general-purpose basis sets continue to be widely used to model core-dependent properties. Core-specialised basis sets are designed with specific features to accurately represent the behaviour of the core region. This design typically incorporates Gaussian primitives with higher exponents to capture core behaviour effectively, as well as some decontraction of basis functions to provide flexibility in describing the core electronic wave function. The highest Gaussian exponent and the degree of contraction for both $s$- and $p$-basis functions effectively characterise these design aspects. In this study, we compare the design and performance of general-purpose basis sets against several literature basis sets specifically designed for three core-dependent properties: J coupling constants, hyperfine coupling constants, and magnetic shielding constants (used for calculating chemical shifts). Our findings consistently demonstrate a significant reduction in error when employing core-specialised basis sets, often at a marginal increase in computational cost compared to the popular 6-31G** basis set. Notably, for expedient calculations of J coupling, hyperfine coupling and magnetic shielding constants, we recommend the use of the pcJ-1, EPR-II, and pcSseg-1, basis sets respectively. For higher accuracy, the pcJ-2, EPR-III, and pcSseg-2 basis sets are recommended.
{"title":"On the Specialisation of Gaussian Basis Sets for Core-Dependent Properties","authors":"Robbie T. Ireland, Laura K. McKemmish","doi":"arxiv-2409.03994","DOIUrl":"https://doi.org/arxiv-2409.03994","url":null,"abstract":"Despite the fact that most quantum chemistry basis sets are designed for\u0000accurately modelling valence chemistry, these general-purpose basis sets\u0000continue to be widely used to model core-dependent properties. Core-specialised\u0000basis sets are designed with specific features to accurately represent the\u0000behaviour of the core region. This design typically incorporates Gaussian\u0000primitives with higher exponents to capture core behaviour effectively, as well\u0000as some decontraction of basis functions to provide flexibility in describing\u0000the core electronic wave function. The highest Gaussian exponent and the degree\u0000of contraction for both $s$- and $p$-basis functions effectively characterise\u0000these design aspects. In this study, we compare the design and performance of general-purpose basis\u0000sets against several literature basis sets specifically designed for three\u0000core-dependent properties: J coupling constants, hyperfine coupling constants,\u0000and magnetic shielding constants (used for calculating chemical shifts). Our\u0000findings consistently demonstrate a significant reduction in error when\u0000employing core-specialised basis sets, often at a marginal increase in\u0000computational cost compared to the popular 6-31G** basis set. Notably, for\u0000expedient calculations of J coupling, hyperfine coupling and magnetic shielding\u0000constants, we recommend the use of the pcJ-1, EPR-II, and pcSseg-1, basis sets\u0000respectively. For higher accuracy, the pcJ-2, EPR-III, and pcSseg-2 basis sets\u0000are recommended.","PeriodicalId":501304,"journal":{"name":"arXiv - PHYS - Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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