Ivo S. Vinklárek, Hubertus Bromberger, Nidin Vadassery, Wuwei Jin, Jochen Küpper, Sebastian Trippel
Water dimer $mathrm{(H_2O)_2}$ - a vital component of the earth's atmosphere - is an important prototypical hydrogen-bonded system. It provides direct insight into fundamental chemical and biochemical processes, e.g., proton transfer and ionic supramolecular dynamics occurring in astro- and atmospheric chemistry. Exploiting a purified molecular beam of water dimer and multi-mass ion imaging, we report the simultaneous detection of all generated ion products of $mathrm{(H_2O)_2^+}$-fragmentation following single ionization. Detailed information about ion yields and reaction energetics of 13 ion-radical pathways, 6 of which are new, of $mathrm{(H_2O)_2^+}$ are presented, including strong $mathrm{{}^{18}O}$-isotope effects.
{"title":"Reaction pathways of water dimer following single ionization","authors":"Ivo S. Vinklárek, Hubertus Bromberger, Nidin Vadassery, Wuwei Jin, Jochen Küpper, Sebastian Trippel","doi":"arxiv-2308.08006","DOIUrl":"https://doi.org/arxiv-2308.08006","url":null,"abstract":"Water dimer $mathrm{(H_2O)_2}$ - a vital component of the earth's atmosphere\u0000- is an important prototypical hydrogen-bonded system. It provides direct\u0000insight into fundamental chemical and biochemical processes, e.g., proton\u0000transfer and ionic supramolecular dynamics occurring in astro- and atmospheric\u0000chemistry. Exploiting a purified molecular beam of water dimer and multi-mass\u0000ion imaging, we report the simultaneous detection of all generated ion products\u0000of $mathrm{(H_2O)_2^+}$-fragmentation following single ionization. Detailed\u0000information about ion yields and reaction energetics of 13 ion-radical\u0000pathways, 6 of which are new, of $mathrm{(H_2O)_2^+}$ are presented, including\u0000strong $mathrm{{}^{18}O}$-isotope effects.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"31 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138542704","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}
The photo-ferrioxalate system (PFS), [Fe(III)(C$_2$O$_4$)]$^{3-}$, more than an exact chemical actinometer, has been extensively applied in wastewater and environment treatment. Despite many experimental efforts to improve clarity, important aspects of the mechanism of ferrioxalate photolysis are still under debate. In this paper, we employ the recently developed W$Gamma$-CASSCF to investigate the ligand-to-metal charge-transfer states key to the ferrioxalate photolysis. This investigation provides a qualitative picture of these states and key potential energy surface features related to the photolysis. Our theoretical results are consistent with the prompt charge transfer picture seen in recent experiments and clarify some features that are not visible in experiments. Two ligand-to-metal charge-transfer states contribute to the photolysis of ferrioxalate, and the avoided crossing barrier between them is low compared to the initial photoexcitation energy. Our data also clarify that one Fe-O bond cleaves first, followed by the C-C bond and the other Fe-O bond.
{"title":"Exploring Ligand-to-Metal Charge-transfer States in the Photo-Ferrioxalate System using Excited-State Specific Optimization","authors":"Lan Nguyen Tran, Eric Neuscamman","doi":"arxiv-2308.04932","DOIUrl":"https://doi.org/arxiv-2308.04932","url":null,"abstract":"The photo-ferrioxalate system (PFS), [Fe(III)(C$_2$O$_4$)]$^{3-}$, more than\u0000an exact chemical actinometer, has been extensively applied in wastewater and\u0000environment treatment. Despite many experimental efforts to improve clarity,\u0000important aspects of the mechanism of ferrioxalate photolysis are still under\u0000debate. In this paper, we employ the recently developed W$Gamma$-CASSCF to\u0000investigate the ligand-to-metal charge-transfer states key to the ferrioxalate\u0000photolysis. This investigation provides a qualitative picture of these states\u0000and key potential energy surface features related to the photolysis. Our\u0000theoretical results are consistent with the prompt charge transfer picture seen\u0000in recent experiments and clarify some features that are not visible in\u0000experiments. Two ligand-to-metal charge-transfer states contribute to the\u0000photolysis of ferrioxalate, and the avoided crossing barrier between them is\u0000low compared to the initial photoexcitation energy. Our data also clarify that\u0000one Fe-O bond cleaves first, followed by the C-C bond and the other Fe-O bond.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"0 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522878","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}
We show that noisy non-unitary dynamics of bosons drives arbitrary initial states into a novel fluctuating bunching state, where all bosons occupy one time-dependent mode. We propose a concept of the noisy spectral gap, a generalization of the spectral gap in noiseless systems, and demonstrate that exponentially fast absorption to the fluctuating bunching state takes place asymptotically. The fluctuating bunching state is unique to noisy non-unitary dynamics with no counterpart in any unitary dynamics and non-unitary dynamics described by a time-independent generator. We also argue that the times of relaxation to the fluctuating bunching state obey a universal power law as functions of the noise parameter in generic noisy non-unitary dynamics.
{"title":"Absorption to Fluctuating Bunching States in Non-Unitary Boson Dynamics","authors":"Ken Mochizuki, Ryusuke Hamazaki","doi":"arxiv-2308.04716","DOIUrl":"https://doi.org/arxiv-2308.04716","url":null,"abstract":"We show that noisy non-unitary dynamics of bosons drives arbitrary initial\u0000states into a novel fluctuating bunching state, where all bosons occupy one\u0000time-dependent mode. We propose a concept of the noisy spectral gap, a\u0000generalization of the spectral gap in noiseless systems, and demonstrate that\u0000exponentially fast absorption to the fluctuating bunching state takes place\u0000asymptotically. The fluctuating bunching state is unique to noisy non-unitary\u0000dynamics with no counterpart in any unitary dynamics and non-unitary dynamics\u0000described by a time-independent generator. We also argue that the times of\u0000relaxation to the fluctuating bunching state obey a universal power law as\u0000functions of the noise parameter in generic noisy non-unitary dynamics.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522881","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}
Tomos Wells, Matthew Foulkes, Andrew Horsfield, Sergei Dudarev
Classical models of spin-lattice coupling are at present unable to accurately reproduce results for numerous properties of ferromagnetic materials, such as heat transport coefficients or the sudden collapse of the magnetic moment in hcp-Fe under pressure. This inability has been attributed to the absence of a proper treatment of effects that are inherently quantum mechanical in nature, notably spin-orbit coupling. This paper introduces a time-dependent, non-collinear tight binding model, complete with spin-orbit coupling and vector Stoner exchange terms, that is capable of simulating the Einstein-de Haas effect in a ferromagnetic $textrm{Fe}_{15}$ cluster. The tight binding model is used to investigate the adiabaticity timescales that determine the response of the orbital and spin angular momenta to a rotating, externally applied $B$ field, and we show that the qualitative behaviours of our simulations can be extrapolated to realistic timescales by use of the adiabatic theorem. An analysis of the trends in the torque contributions with respect to the field strength demonstrates that SOC is necessary to observe a transfer of angular momentum from the electrons to the nuclei at experimentally realistic $B$ fields. The simulations presented in this paper demonstrate the Einstein-de Haas effect from first principles using a Fe cluster.
{"title":"The Einstein-de Haas Effect in an $textrm{Fe}_{15}$ Cluster","authors":"Tomos Wells, Matthew Foulkes, Andrew Horsfield, Sergei Dudarev","doi":"arxiv-2308.03130","DOIUrl":"https://doi.org/arxiv-2308.03130","url":null,"abstract":"Classical models of spin-lattice coupling are at present unable to accurately\u0000reproduce results for numerous properties of ferromagnetic materials, such as\u0000heat transport coefficients or the sudden collapse of the magnetic moment in\u0000hcp-Fe under pressure. This inability has been attributed to the absence of a\u0000proper treatment of effects that are inherently quantum mechanical in nature,\u0000notably spin-orbit coupling. This paper introduces a time-dependent,\u0000non-collinear tight binding model, complete with spin-orbit coupling and vector\u0000Stoner exchange terms, that is capable of simulating the Einstein-de Haas\u0000effect in a ferromagnetic $textrm{Fe}_{15}$ cluster. The tight binding model\u0000is used to investigate the adiabaticity timescales that determine the response\u0000of the orbital and spin angular momenta to a rotating, externally applied $B$\u0000field, and we show that the qualitative behaviours of our simulations can be\u0000extrapolated to realistic timescales by use of the adiabatic theorem. An\u0000analysis of the trends in the torque contributions with respect to the field\u0000strength demonstrates that SOC is necessary to observe a transfer of angular\u0000momentum from the electrons to the nuclei at experimentally realistic $B$\u0000fields. The simulations presented in this paper demonstrate the Einstein-de\u0000Haas effect from first principles using a Fe cluster.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522877","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}
Francesco Campaioli, Stefano Gherardini, James Q. Quach, Marco Polini, Gian Marcello Andolina
Recent years have witnessed an explosion of interest in quantum devices for the production, storage, and transfer of energy. In this Colloquium, we concentrate on the field of quantum energy storage by reviewing recent theoretical and experimental progress in quantum batteries. We first provide a theoretical background discussing the advantages that quantum batteries offer with respect to their classical analogues. We then review the existing quantum many-body battery models and present a thorough discussion of important issues related to their open nature. We finally conclude by discussing promising experimental implementations, preliminary results available in the literature, and perspectives.
{"title":"Colloquium: Quantum Batteries","authors":"Francesco Campaioli, Stefano Gherardini, James Q. Quach, Marco Polini, Gian Marcello Andolina","doi":"arxiv-2308.02277","DOIUrl":"https://doi.org/arxiv-2308.02277","url":null,"abstract":"Recent years have witnessed an explosion of interest in quantum devices for\u0000the production, storage, and transfer of energy. In this Colloquium, we\u0000concentrate on the field of quantum energy storage by reviewing recent\u0000theoretical and experimental progress in quantum batteries. We first provide a\u0000theoretical background discussing the advantages that quantum batteries offer\u0000with respect to their classical analogues. We then review the existing quantum\u0000many-body battery models and present a thorough discussion of important issues\u0000related to their open nature. We finally conclude by discussing promising\u0000experimental implementations, preliminary results available in the literature,\u0000and perspectives.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"32 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522875","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}
Velocity map imaging (VMI) is a powerful technique that allows to infer the kinetic energy of ions or electrons that are produced from a large volume in space with good resolution. The size of the acceptance volume is determined by the spherical aberrations of the ion optical system. Here we present an analytical derivation for velocity map imaging with no spherical aberrations. We will discuss a particular example for the implementation of the technique that allows using the reaction microscope recently installed in the Cryogenic storage ring (CSR) in a VMI mode. SIMION simulations confirm that a beam of electrons produced almost over the entire volume of the source region, with width of 8 cm, can be focused to a spot of 0.1 mm on the detector. The use of the same formalism for position imaging, as well as an option of position imaging in one axis and velocity map imaging in a different axis, are also discussed.
{"title":"Velocity Map Imaging with No Spherical Aberrations","authors":"Yehuda Ben-Shabo, Adeliya Kurbanov, Claus Dieter Schroter, Robert Moshammer, Holger Kreckel, Yoni Toker","doi":"arxiv-2308.01005","DOIUrl":"https://doi.org/arxiv-2308.01005","url":null,"abstract":"Velocity map imaging (VMI) is a powerful technique that allows to infer the\u0000kinetic energy of ions or electrons that are produced from a large volume in\u0000space with good resolution. The size of the acceptance volume is determined by\u0000the spherical aberrations of the ion optical system. Here we present an\u0000analytical derivation for velocity map imaging with no spherical aberrations.\u0000We will discuss a particular example for the implementation of the technique\u0000that allows using the reaction microscope recently installed in the Cryogenic\u0000storage ring (CSR) in a VMI mode. SIMION simulations confirm that a beam of\u0000electrons produced almost over the entire volume of the source region, with\u0000width of 8 cm, can be focused to a spot of 0.1 mm on the detector. The use of\u0000the same formalism for position imaging, as well as an option of position\u0000imaging in one axis and velocity map imaging in a different axis, are also\u0000discussed.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"177 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522872","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}
Harald W. GriesshammerGeorge Washington U., Ubirajara van KolckCNRS/IN2P3 and U. of Arizona
"Resummed-Range Effective Field Theory'' is a consistent nonrelativistic effective field theory of contact interactions with large scattering length $a$ and an effective range $r_0$ large in magnitude but negative. Its leading order is non-perturbative. Its observables are universal, i.e.~they depend only on the dimensionless ratio $xi:=2r_0/a$, with the overall distance scale set by $|r_0|$. In the two-body sector, the position of the two shallow $S$-wave poles in the complex plane is determined by $xi$. We investigate three identical bosons at leading order for a two-body system with one bound and one virtual state ($xile0$), or with two virtual states ($0lexi<1$). Such conditions might, for example, be found in systems of heavy mesons. We find that no three-body interaction is needed to renormalise (and stabilise) Resummed-Range EFT at LO. A well-defined ground state exists for $0.366ldotslexile-8.72ldots$. Three-body excitations appear for even smaller ranges of $xi$ around the ``quasi-unitarity point'' $xi=0$ ($|r_0|ll|a|toinfty$) and obey discrete scaling relations. We explore in detail the ground state and the lowest three excitations and parametrise their trajectories as function of $xi$ and of the binding momentum $kappa_2^-$ of the shallowest twoB state from where three-body and two-body binding energies are identical to zero three-body binding. As $|r_0|ll|a|$ becomes perturbative, this version turns into the ``Short-Range EFT'' which needs a stabilising three-body interaction and exhibits Efimov's Discrete Scale Invariance. By interpreting that EFT as a low-energy version of Resummed-Range EFT, we match spectra to determine Efimov's scale-breaking parameter $Lambda_*$ in a renormalisation scheme with a ``hard'' cutoff. Finally, we compare phase shifts for scattering a boson on the two-boson bound state with that of the equivalent Efimov system.
{"title":"Universality of Three Identical Bosons with Large, Negative Effective Range","authors":"Harald W. GriesshammerGeorge Washington U., Ubirajara van KolckCNRS/IN2P3 and U. of Arizona","doi":"arxiv-2308.01394","DOIUrl":"https://doi.org/arxiv-2308.01394","url":null,"abstract":"\"Resummed-Range Effective Field Theory'' is a consistent nonrelativistic\u0000effective field theory of contact interactions with large scattering length $a$\u0000and an effective range $r_0$ large in magnitude but negative. Its leading order\u0000is non-perturbative. Its observables are universal, i.e.~they depend only on\u0000the dimensionless ratio $xi:=2r_0/a$, with the overall distance scale set by\u0000$|r_0|$. In the two-body sector, the position of the two shallow $S$-wave poles\u0000in the complex plane is determined by $xi$. We investigate three identical\u0000bosons at leading order for a two-body system with one bound and one virtual\u0000state ($xile0$), or with two virtual states ($0lexi<1$). Such conditions\u0000might, for example, be found in systems of heavy mesons. We find that no\u0000three-body interaction is needed to renormalise (and stabilise) Resummed-Range\u0000EFT at LO. A well-defined ground state exists for\u0000$0.366ldotslexile-8.72ldots$. Three-body excitations appear for even\u0000smaller ranges of $xi$ around the ``quasi-unitarity point'' $xi=0$\u0000($|r_0|ll|a|toinfty$) and obey discrete scaling relations. We explore in\u0000detail the ground state and the lowest three excitations and parametrise their\u0000trajectories as function of $xi$ and of the binding momentum $kappa_2^-$ of\u0000the shallowest twoB state from where three-body and two-body binding energies\u0000are identical to zero three-body binding. As $|r_0|ll|a|$ becomes\u0000perturbative, this version turns into the ``Short-Range EFT'' which needs a\u0000stabilising three-body interaction and exhibits Efimov's Discrete Scale\u0000Invariance. By interpreting that EFT as a low-energy version of Resummed-Range\u0000EFT, we match spectra to determine Efimov's scale-breaking parameter\u0000$Lambda_*$ in a renormalisation scheme with a ``hard'' cutoff. Finally, we\u0000compare phase shifts for scattering a boson on the two-boson bound state with\u0000that of the equivalent Efimov system.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138542706","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}
Marianna D'Amato, Lucien Belzane, Corentin Dabard, Mathieu Silly, Gilles Patriarche, Quentin Glorieux, Hanna Le Jeannic, Emmanuel Lhuillier, Alberto Bramati
Achieving pure single-photon emission is essential for a range of quantum technologies, from optical quantum computing to quantum key distribution to quantum metrology. Among solid-state quantum emitters, colloidal lead halide perovskite (LHP) nanocrystals (NCs) have garnered significant attention due to their interesting structural and optical properties, which make them appealing single-photon sources (SPSs). However, their practical utilization for quantum technology applications has been hampered by environment-induced instabilities. In this study, we fabricate and characterize in a systematic manner Zn-treated $CsPbBr_3$ colloidal NCs obtained through $Zn^{2+}$ ion doping at the Pb-site, demonstrating improved stability under dilution and illumination. These doped NCs exhibit high single-photon purity, reduced blinking on a sub-millisecond timescale and stability of the bright state for excitation powers well above the saturation levels. Our findings highlight the potential of this synthesis approach to optimize the performance of LHP-based SPSs, opening up interesting prospects for their integration into nanophotonic systems for quantum technology applications.
{"title":"Highly photostable Zn-treated halide perovskite nanocrystals for efficient single photon generation","authors":"Marianna D'Amato, Lucien Belzane, Corentin Dabard, Mathieu Silly, Gilles Patriarche, Quentin Glorieux, Hanna Le Jeannic, Emmanuel Lhuillier, Alberto Bramati","doi":"arxiv-2307.15959","DOIUrl":"https://doi.org/arxiv-2307.15959","url":null,"abstract":"Achieving pure single-photon emission is essential for a range of quantum\u0000technologies, from optical quantum computing to quantum key distribution to\u0000quantum metrology. Among solid-state quantum emitters, colloidal lead halide\u0000perovskite (LHP) nanocrystals (NCs) have garnered significant attention due to\u0000their interesting structural and optical properties, which make them appealing\u0000single-photon sources (SPSs). However, their practical utilization for quantum\u0000technology applications has been hampered by environment-induced instabilities.\u0000In this study, we fabricate and characterize in a systematic manner Zn-treated\u0000$CsPbBr_3$ colloidal NCs obtained through $Zn^{2+}$ ion doping at the Pb-site,\u0000demonstrating improved stability under dilution and illumination. These doped\u0000NCs exhibit high single-photon purity, reduced blinking on a sub-millisecond\u0000timescale and stability of the bright state for excitation powers well above\u0000the saturation levels. Our findings highlight the potential of this synthesis\u0000approach to optimize the performance of LHP-based SPSs, opening up interesting\u0000prospects for their integration into nanophotonic systems for quantum\u0000technology applications.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522882","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}
The aggregation of particles in the free molecular regime pertaining to cluster growth is determined approximately for kernels describing frequently occurring physical situations. The mean particle sizes develop close to linearly in time. Scaling relations are used to derive a linear partial differential equation which is solved to show that the size distributions are close to log-normal size distributions asymptotically in time.
{"title":"Size distributions in irreversible particle aggregation","authors":"Klavs Hansen","doi":"arxiv-2307.14795","DOIUrl":"https://doi.org/arxiv-2307.14795","url":null,"abstract":"The aggregation of particles in the free molecular regime pertaining to\u0000cluster growth is determined approximately for kernels describing frequently\u0000occurring physical situations. The mean particle sizes develop close to\u0000linearly in time. Scaling relations are used to derive a linear partial\u0000differential equation which is solved to show that the size distributions are\u0000close to log-normal size distributions asymptotically in time.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"62 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522871","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}
We performed a systematic first-principles study on vibrationally-resolved X-ray absorption (XAS) and photoelectron (XPS) spectra of a series of diatomic molecules and cations (XAS, N$_2$, N$_2^+$, NO$^+$, CO, CO$^+$; XPS, CO) at the C/N/O K-edges. All computations were done in a time-independent (TI) framework under the harmonic oscillator approximation. To evaluate the performance of different functionals, two common pure (BLYP and BP86) and two hybrid (B3LYP and M06-2X) functionals were used. Excellent agreement between theoretical and experimental spectra was observed in most systems. Two instances, where the peak separations were underestimated, were seen in the O1s XAS spectra of CO and NO$^+$, and we explain this discrepancy to the anharmonic effects. The functional dependence can be evident or negligible, depending on the specific system and spectrum under consideration. In all these examples, the pure functionals exhibit a better or similar spectral accuracy to the hybrid functionals. This was attributed to better accuracy in bond lengths and vibrational frequencies (in both the initial and final states) predicted by pure functionals, as compared with the experiments. Structural and frequency changes induced by the core hole were summarized. We highlight the use of density functional theory with pure functionals for such diatomic calculations for easy execution and generally reliable accuracy.
{"title":"Vibrationally-resolved X-ray spectra of diatomic systems. I. Time-independent simulations with density functional theory","authors":"Lu Zhang, Minrui Wei, Guoyan Ge, Weijie Hua","doi":"arxiv-2307.14207","DOIUrl":"https://doi.org/arxiv-2307.14207","url":null,"abstract":"We performed a systematic first-principles study on vibrationally-resolved\u0000X-ray absorption (XAS) and photoelectron (XPS) spectra of a series of diatomic\u0000molecules and cations (XAS, N$_2$, N$_2^+$, NO$^+$, CO, CO$^+$; XPS, CO) at the\u0000C/N/O K-edges. All computations were done in a time-independent (TI) framework\u0000under the harmonic oscillator approximation. To evaluate the performance of\u0000different functionals, two common pure (BLYP and BP86) and two hybrid (B3LYP\u0000and M06-2X) functionals were used. Excellent agreement between theoretical and\u0000experimental spectra was observed in most systems. Two instances, where the\u0000peak separations were underestimated, were seen in the O1s XAS spectra of CO\u0000and NO$^+$, and we explain this discrepancy to the anharmonic effects. The\u0000functional dependence can be evident or negligible, depending on the specific\u0000system and spectrum under consideration. In all these examples, the pure\u0000functionals exhibit a better or similar spectral accuracy to the hybrid\u0000functionals. This was attributed to better accuracy in bond lengths and\u0000vibrational frequencies (in both the initial and final states) predicted by\u0000pure functionals, as compared with the experiments. Structural and frequency\u0000changes induced by the core hole were summarized. We highlight the use of\u0000density functional theory with pure functionals for such diatomic calculations\u0000for easy execution and generally reliable accuracy.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"72 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522880","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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