Pub Date : 2020-01-18DOI: 10.1103/PHYSREVRESEARCH.2.032051
A. Jasinski, J. Montaner, R. C. Forrey, B. Yang, P. Stancil, N. Balakrishnan, J. Dai, R. A. Vargas-Hern'andez, R. Krems
Quantum scattering calculations for all but low-dimensional systems at low energies must rely on approximations. All approximations introduce errors. The impact of these errors is often difficult to assess because they depend on the Hamiltonian parameters and the particular observable under study. Here, we illustrate a general, system and approximation-independent, approach to improve the accuracy of quantum dynamics approximations. The method is based on a Bayesian machine learning (BML) algorithm that is trained by a small number of rigorous results and a large number of approximate calculations, resulting in ML models that accurately capture the dependence of the dynamics results on the quantum dynamics parameters. Most importantly, the present work demonstrates that the BML models can generalize quantum results to different dynamical processes. Thus, a ML model trained by a combination of approximate and rigorous results for a certain inelastic transition can make accurate predictions for different transitions without rigorous calculations. This opens the possibility of improving the accuracy of approximate calculations for quantum transitions that are out of reach of rigorous scattering calculations.
{"title":"Machine learning corrected quantum dynamics calculations","authors":"A. Jasinski, J. Montaner, R. C. Forrey, B. Yang, P. Stancil, N. Balakrishnan, J. Dai, R. A. Vargas-Hern'andez, R. Krems","doi":"10.1103/PHYSREVRESEARCH.2.032051","DOIUrl":"https://doi.org/10.1103/PHYSREVRESEARCH.2.032051","url":null,"abstract":"Quantum scattering calculations for all but low-dimensional systems at low energies must rely on approximations. All approximations introduce errors. The impact of these errors is often difficult to assess because they depend on the Hamiltonian parameters and the particular observable under study. Here, we illustrate a general, system and approximation-independent, approach to improve the accuracy of quantum dynamics approximations. The method is based on a Bayesian machine learning (BML) algorithm that is trained by a small number of rigorous results and a large number of approximate calculations, resulting in ML models that accurately capture the dependence of the dynamics results on the quantum dynamics parameters. Most importantly, the present work demonstrates that the BML models can generalize quantum results to different dynamical processes. Thus, a ML model trained by a combination of approximate and rigorous results for a certain inelastic transition can make accurate predictions for different transitions without rigorous calculations. This opens the possibility of improving the accuracy of approximate calculations for quantum transitions that are out of reach of rigorous scattering calculations.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":"8 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74755224","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}
Pub Date : 2020-01-10DOI: 10.1016/j.rinp.2020.103078
U. Okorie, A. Ikot, E. Chukwuocha
{"title":"Thermodynamic properties of improved deformed exponential-type potential (IDEP) for some diatomic molecules","authors":"U. Okorie, A. Ikot, E. Chukwuocha","doi":"10.1016/j.rinp.2020.103078","DOIUrl":"https://doi.org/10.1016/j.rinp.2020.103078","url":null,"abstract":"","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84381618","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}
This review presents the main principles underlying the theoretical description of the behavior of regular and random arrays of nanometric active sites. It is further shown how they can be applied for establishing a useful semi-analytical approximation of the arrays responses under diffusion limited conditions when they involve the common situation of active sites with identical sizes. This approximation is general and, as exemplified for different type of arrays, can be employed for describing the behavior of any array involving arbitrary distributions of their active sites onto the substrate surface. Furthermore, this efficient approach allows statistical characterization of active sites distributions of any array based on chronoamperometric data.
{"title":"Editors' Choice—Review—Nanostructured Electrodes as Random Arrays of Active Sites: Modeling and Theoretical Characterization","authors":"A. Oleinick, O. Sliusarenko, I. Svir, C. Amatore","doi":"10.1149/2.0302001JES","DOIUrl":"https://doi.org/10.1149/2.0302001JES","url":null,"abstract":"This review presents the main principles underlying the theoretical description of the behavior of regular and random arrays of nanometric active sites. It is further shown how they can be applied for establishing a useful semi-analytical approximation of the arrays responses under diffusion limited conditions when they involve the common situation of active sites with identical sizes. This approximation is general and, as exemplified for different type of arrays, can be employed for describing the behavior of any array involving arbitrary distributions of their active sites onto the substrate surface. Furthermore, this efficient approach allows statistical characterization of active sites distributions of any array based on chronoamperometric data.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":"67 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91219125","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}
Pub Date : 2019-12-24DOI: 10.26434/chemrxiv.11441067.v1
Y. Scolnik
Circular dichroism spectra were recorded for micellar aggregates of N-stearoyl (L or D) serine in H2O or D2O. Micelle formation kinetics differed markedly in H2O, but in D2O the enantiomers showed similar spectral characteristics. The results confirm previous observations (1) that described differences in the thermodynamic properties of enantiomers, in contrary to the reigning dogma. The comparison of spectral properties indicates that this phenomenon depends on the interactions with H2O and is not due to trivial contamination.
{"title":"Mirror Symmetry Breaking in Micelles of N-Stearoyl Serine Enantiomers","authors":"Y. Scolnik","doi":"10.26434/chemrxiv.11441067.v1","DOIUrl":"https://doi.org/10.26434/chemrxiv.11441067.v1","url":null,"abstract":"Circular dichroism spectra were recorded for micellar aggregates of N-stearoyl (L or D) serine in H2O or D2O. Micelle formation kinetics differed markedly in H2O, but in D2O the enantiomers showed similar spectral characteristics. The results confirm previous observations (1) that described differences in the thermodynamic properties of enantiomers, in contrary to the reigning dogma. The comparison of spectral properties indicates that this phenomenon depends on the interactions with H2O and is not due to trivial contamination.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77645236","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}
Pub Date : 2019-12-23DOI: 10.1103/PhysRevResearch.1.033195
S. Porada, H. Hamelers, P. M. Biesheuvel
Electrostatic cooling is known to occur in conductors and in porous electrodes in contact with aqueous electrolytes. Here we present for the first time evidence of electrostatic cooling at the junction of two electrolyte phases. These are, first, water containing salt, and, second, an ion-exchange membrane, which is a water-filled porous layer containing a large concentration of fixed charges. When ionic current is directed through such a membrane in contact with aqueous phases on both sides, a temperature difference develops across the membrane which rapidly switches sign when the current direction is reversed. The temperature difference develops because one water-membrane junction cools down, while the other heats up. Cooling takes place when the inner product of ionic current $textbf{I}$ and field strength $textbf{E}$ is a negative quantity, which is possible in the electrical double layers that form on the surface of the membrane. Theory reproduces the magnitude of the effect but overestimates the rate by which the temperature difference across the membrane adjusts itself to a reversal in current.
{"title":"Electrostatic cooling at electrolyte-electrolyte junctions","authors":"S. Porada, H. Hamelers, P. M. Biesheuvel","doi":"10.1103/PhysRevResearch.1.033195","DOIUrl":"https://doi.org/10.1103/PhysRevResearch.1.033195","url":null,"abstract":"Electrostatic cooling is known to occur in conductors and in porous electrodes in contact with aqueous electrolytes. Here we present for the first time evidence of electrostatic cooling at the junction of two electrolyte phases. These are, first, water containing salt, and, second, an ion-exchange membrane, which is a water-filled porous layer containing a large concentration of fixed charges. When ionic current is directed through such a membrane in contact with aqueous phases on both sides, a temperature difference develops across the membrane which rapidly switches sign when the current direction is reversed. The temperature difference develops because one water-membrane junction cools down, while the other heats up. Cooling takes place when the inner product of ionic current $textbf{I}$ and field strength $textbf{E}$ is a negative quantity, which is possible in the electrical double layers that form on the surface of the membrane. Theory reproduces the magnitude of the effect but overestimates the rate by which the temperature difference across the membrane adjusts itself to a reversal in current.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":"65 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76208615","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}
Hierarchical equations of motion approach with the Drude-Lorentz spectral density has been widely employed in investigating quantum dissipative phenomena. However, it is often computationally costly for low-temperature systems because a number of Matsubara frequencies are involved. In this note, we examine a prerequisite required for spectral density, and demonstrate that relevant spectral density may significantly reduce the number of Matsubara terms to obtain convergent results for low temperatures.
{"title":"Prerequisites for Relevant Spectral Density and Convergence of Reduced Density Matrices at Low Temperatures","authors":"A. Ishizaki","doi":"10.7566/JPSJ.89.015001","DOIUrl":"https://doi.org/10.7566/JPSJ.89.015001","url":null,"abstract":"Hierarchical equations of motion approach with the Drude-Lorentz spectral density has been widely employed in investigating quantum dissipative phenomena. However, it is often computationally costly for low-temperature systems because a number of Matsubara frequencies are involved. In this note, we examine a prerequisite required for spectral density, and demonstrate that relevant spectral density may significantly reduce the number of Matsubara terms to obtain convergent results for low temperatures.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85509437","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}
Double hybrid density functional theory arguably sits on the seamline between wavefunction methods and DFT: it represents a special case of Rung 5 on the "Jacobs Ladder" of John P. Perdew. For large and chemically diverse benchmarks such as GMTKN55, empirical double hybrid functionals with dispersion corrections can achieve accuracies approaching wavefunction methods at a cost not greatly dissimilar to hybrid DFT approaches, provided RI-MP2 and/or another MP2 acceleration techniques are available in the electronic structure code. Only a half-dozen or fewer empirical parameters are required. For vibrational frequencies, accuracies intermediate between CCSD and CCSD(T) can be achieved, and performance for other properties is encouraging as well. Organometallic reactions can likewise be treated well, provided static correlation is not too strong. Further prospects are discussed, including range-separated and RPA-based approaches.
双混合密度泛函理论可以说是位于波函数方法和DFT之间的边界上:它代表了John P. Perdew的“雅各布斯阶梯”第5级的特殊情况。对于像GMTKN55这样的大型和化学多样性基准，具有色散校正的经验双重混合泛函可以达到接近波函数方法的精度，其成本与混合DFT方法相差不大，前提是RI-MP2和/或其他MP2加速技术在电子结构代码中可用。只需要六个或更少的经验参数。对于振动频率，可以实现介于CCSD和CCSD(T)之间的精度，并且其他特性的性能也令人鼓舞。如果静态相关性不太强，有机金属反应同样可以处理得很好。讨论了进一步的前景，包括范围分离和基于rpa的方法。
{"title":"Empirical Double‐Hybrid Density Functional Theory: A ‘Third Way’ in Between WFT and DFT","authors":"Jan M. L. Martin, Golokesh Santra","doi":"10.1002/ijch.201900114","DOIUrl":"https://doi.org/10.1002/ijch.201900114","url":null,"abstract":"Double hybrid density functional theory arguably sits on the seamline between wavefunction methods and DFT: it represents a special case of Rung 5 on the \"Jacobs Ladder\" of John P. Perdew. For large and chemically diverse benchmarks such as GMTKN55, empirical double hybrid functionals with dispersion corrections can achieve accuracies approaching wavefunction methods at a cost not greatly dissimilar to hybrid DFT approaches, provided RI-MP2 and/or another MP2 acceleration techniques are available in the electronic structure code. Only a half-dozen or fewer empirical parameters are required. For vibrational frequencies, accuracies intermediate between CCSD and CCSD(T) can be achieved, and performance for other properties is encouraging as well. Organometallic reactions can likewise be treated well, provided static correlation is not too strong. Further prospects are discussed, including range-separated and RPA-based approaches.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":"44 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80801705","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}
Sodium-ion batteries (SIBs) have received significant attention as promising alternative for energy storage applications owing to the large availability and low cost of sodium. In this paper we study the electrochemical behavior of Na$_{0.74}$Co$_{1-x}$Nb$_x$O$_2$ ($x=$ 0 and 0.05 samples), synthesized via solid-state reaction. The Rietveld refinement of x-ray diffraction patterns reveals the hexagonal crystal symmetry with P63/mmc space group. The Na$_{0.74}$Co$_{0.95}$Nb$_{0.05}$O$_2$ cathode exhibits a specific capacity of about 91 mAhg$^{-1}$ at a current density of 6 mAg$^{-1}$, whereas Na$_{0.74}$CoO$_2$ exhibits comparatively low specific capacity (70 mAhg$^{-1}$ at a current density of 6 mAg$^{-1}$). The cyclic voltammetry (CV) and electron impedance spectroscopy (EIS) were performed to determine the diffusion coefficient of Na, which found to be in the range of 10$^{-10}$ cm$^2$s$^{-1}$.
{"title":"Electrochemical analysis of Na0.7Co1-xNbxO2(x = 0, 0.05) as cathode materials in sodium-ion batteries","authors":"J. Pati, M. Chandra, R. Dhaka","doi":"10.1063/5.0016704","DOIUrl":"https://doi.org/10.1063/5.0016704","url":null,"abstract":"Sodium-ion batteries (SIBs) have received significant attention as promising alternative for energy storage applications owing to the large availability and low cost of sodium. In this paper we study the electrochemical behavior of Na$_{0.74}$Co$_{1-x}$Nb$_x$O$_2$ ($x=$ 0 and 0.05 samples), synthesized via solid-state reaction. The Rietveld refinement of x-ray diffraction patterns reveals the hexagonal crystal symmetry with P63/mmc space group. The Na$_{0.74}$Co$_{0.95}$Nb$_{0.05}$O$_2$ cathode exhibits a specific capacity of about 91 mAhg$^{-1}$ at a current density of 6 mAg$^{-1}$, whereas Na$_{0.74}$CoO$_2$ exhibits comparatively low specific capacity (70 mAhg$^{-1}$ at a current density of 6 mAg$^{-1}$). The cyclic voltammetry (CV) and electron impedance spectroscopy (EIS) were performed to determine the diffusion coefficient of Na, which found to be in the range of 10$^{-10}$ cm$^2$s$^{-1}$.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":"134 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77907797","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}
Pub Date : 2019-09-26DOI: 10.1016/J.PHYSD.2021.132929
I. Domagalska, M. Jarosik, A. Durajski, J. K. Kalaga, R. Szczesniak
{"title":"Chaotic evolution of the energy of the electron orbital and the hopping integral in diatomic molecule cations subjected to harmonic excitation","authors":"I. Domagalska, M. Jarosik, A. Durajski, J. K. Kalaga, R. Szczesniak","doi":"10.1016/J.PHYSD.2021.132929","DOIUrl":"https://doi.org/10.1016/J.PHYSD.2021.132929","url":null,"abstract":"","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87150995","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}
Pub Date : 2019-08-16DOI: 10.26434/chemrxiv.9638810
S. Kristyán
The non-relativistic electronic Hamiltonian, H(a)= Hkin+Hne+aHee, extended with coupling strength parameter (a), allows to switch the electron-electron repulsion energy off and on. First, the easier a=0 case is solved and the solution of real (physical) a=1 case is generated thereafter from it to calculate the total electronic energy (Etotal electr,K) mainly for ground state (K=0). This strategy is worked out with utilizing generalized Moller-Plesset (MP), square of Hamiltonian (H2) and Configuration interactions (CI) devices. Applying standard eigensolver for Hamiltonian matrices (one or two times) buys off the needs of self-consistent field (SCF) convergence in this algorithm, along with providing the correction for basis set error and correlation effect. (SCF convergence is typically performed in the standard HF-SCF/basis/a=1 routine in today practice.)
{"title":"Solving the Non-Relativistic Electronic Schrödinger Equation with Manipulating the Coupling Strength Parameter over the Electron-Electron Coulomb Integrals","authors":"S. Kristyán","doi":"10.26434/chemrxiv.9638810","DOIUrl":"https://doi.org/10.26434/chemrxiv.9638810","url":null,"abstract":"The non-relativistic electronic Hamiltonian, H(a)= Hkin+Hne+aHee, extended with coupling strength parameter (a), allows to switch the electron-electron repulsion energy off and on. First, the easier a=0 case is solved and the solution of real (physical) a=1 case is generated thereafter from it to calculate the total electronic energy (Etotal electr,K) mainly for ground state (K=0). This strategy is worked out with utilizing generalized Moller-Plesset (MP), square of Hamiltonian (H2) and Configuration interactions (CI) devices. Applying standard eigensolver for Hamiltonian matrices (one or two times) buys off the needs of self-consistent field (SCF) convergence in this algorithm, along with providing the correction for basis set error and correlation effect. (SCF convergence is typically performed in the standard HF-SCF/basis/a=1 routine in today practice.)","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":"70 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73875213","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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