arXiv: Chemical Physics最新文献_第2页

Hidden duality and accidental degeneracy in cycloacene and Möbius cycloacene 环二烯和Möbius环二烯的隐性对偶和偶然简并

arXiv: Chemical Physics Pub Date : 2020-08-05 DOI: 10.1063/5.0031586

E. Sadurní, F. Leyvraz, T. Stegmann, T. Seligman, D. Klein

引用次数: 3

The seniority quantum number in Tensor Network States 张量网络状态中的优先量子数

arXiv: Chemical Physics Pub Date : 2020-08-03 DOI: 10.21468/SCIPOSTCHEM.1.1.001

Klaas Gunst, D. Neck, P. Limacher, S. Baerdemacker

引用次数: 3

A Neural Network Inspired Formulation of Chemical Kinetics 一个受神经网络启发的化学动力学公式

arXiv: Chemical Physics Pub Date : 2020-07-31 DOI: 10.3390/en14092710

S. Barwey, V. Raman

{"title":"A Neural Network Inspired Formulation of Chemical Kinetics","authors":"S. Barwey, V. Raman","doi":"10.3390/en14092710","DOIUrl":"https://doi.org/10.3390/en14092710","url":null,"abstract":"A method which casts the chemical source term computation into an artificial neural network (ANN)-inspired form is presented. This approach is well-suited for use on emerging supercomputing platforms that rely on graphical processing units (GPUs). The resulting equations allow for a GPU-friendly matrix-multiplication based source term estimation where the leading dimension (batch size) can be interpreted as the number of chemically reacting cells in the domain; as such, the approach can be readily adapted in high-fidelity solvers for which an MPI rank offloads the source term computation task for a given number of cells to the GPU. Though the exact ANN-inspired recasting shown here is optimal for GPU environments as-is, this interpretation allows the user to replace portions of the exact routine with trained, so-called approximate ANNs, where the goal of these approximate ANNs is to increase computational efficiency over the exact routine counterparts. Note that the main objective of this paper is not to use machine learning for developing models, but rather to represent chemical kinetics using the ANN framework. The end result is that little-to-no training is needed, and the GPU-friendly structure of the ANN formulation during the source term computation is preserved. The method is demonstrated using chemical mechanisms of varying complexity on both 0-D auto-ignition and 1-D channel detonation problems, and the details of performance on GPUs are explored.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89218345","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}

引用次数: 1

Proton-transfer dynamics in ionized water chains using real-time time-dependent density functional theory 利用实时时变密度泛函理论的离子水链中的质子转移动力学

arXiv: Chemical Physics Pub Date : 2020-07-22 DOI: 10.1103/physrevresearch.2.043082

Vidushi Sharma, M. Fernández-Serra

{"title":"Proton-transfer dynamics in ionized water chains using real-time time-dependent density functional theory","authors":"Vidushi Sharma, M. Fernández-Serra","doi":"10.1103/physrevresearch.2.043082","DOIUrl":"https://doi.org/10.1103/physrevresearch.2.043082","url":null,"abstract":"In density functional-theoretic studies of photoionized water-based systems, the role of charge localization in proton-transfer dynamics is not well understood. This is due to the inherent complexity in extracting the contributions of coupled electron-nuclear non-adiabatic dynamics in the presence of exchange and correlation functional errors. In this work, we address this problem by simulating a model system of ionized linear H-bonded water clusters using real-time Time Dependent Density Functional Theory (rt-TDDFT)-based Ehrenfest dynamics. Our aim is to understand how self-interaction error in semilocal exchange and correlation functionals affects the probability of proton transfer. In particular, we show that for H-bonded (H$_2$O)$_n^+$ chains (with $n>3$), the proton-transfer probability attains a maximum, becoming comparable to that predicted by hybrid functionals. This is because the formation of hemibonded-type geometries is largely suppressed in extended H-bonded structures. We also show how the degree of localization of the initial photo-hole is connected to the probability of a proton-transfer reaction, as well as to the separation between electronic and nuclear charge. These results are compared to those obtained with adiabatic dynamics where the initial wavefunction is allowed to relax to the ground state of the ion cluster, explaining why different functionals and dynamical approaches lead to quantitatively different results.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77589289","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}

引用次数: 1

Vibrational sum frequency scattering in absorptive media: A theoretical case study of nano-objects water 吸收介质中的振动和频率散射:纳米物体水的理论研究

arXiv: Chemical Physics Pub Date : 2020-07-21 DOI: 10.1021/acs.jpcc.0c05196.s001

S. Kulik, S. Pullanchery, S. Roke

{"title":"Vibrational sum frequency scattering in absorptive media: A theoretical case study of nano-objects water","authors":"S. Kulik, S. Pullanchery, S. Roke","doi":"10.1021/acs.jpcc.0c05196.s001","DOIUrl":"https://doi.org/10.1021/acs.jpcc.0c05196.s001","url":null,"abstract":"The structures of interfaces of nano- and microscale objects in aqueous solution are important for a wide variety of physical, chemical and biological processes. Vibrational sum frequency scattering has emerged as a useful and unique probe of the interfacial structure of nano- and microscale objects in water. However, the full surface vibrational stretch mode spectrum has not been measured yet, even though it would be extremely informative to do so. The reason for this is that probing the vibrational modes of interfacial water requires a full understanding of how the linear absorptive properties of the bulk aqueous medium influence the sum frequency scattering process. Here, we have simulated vibrational sum frequency scattering spectra of the interface of nanoscale objects dispersed in water. We analyzed the effect of the infrared pulse absorption on the outcome of surface vibrational sum frequency scattering measurements. We find that both infrared absorption as well as the type of optical detection can drastically modify the measured vibrational interfacial spectrum. The observed changes comprise spectral distortion, frequency shifting of the main vibrational stretch mode and the introducing of a new high frequency peak. This last feature is enhanced by non-resonant interactions.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80343279","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}

引用次数: 1

Critical Benchmarking of the G4(MP2) Model, the Correlation Consistent Composite Approach and Popular Density Functional Approximations on a Probabilistically Pruned Benchmark Dataset of Formation Enthalpies G4(MP2)模型的临界基准测试、相关一致复合方法和基于概率剪枝生成焓基准数据集的流行密度泛函逼近

arXiv: Chemical Physics Pub Date : 2020-07-13 DOI: 10.26434/chemrxiv.12647033.v1

Sambit Das, S. Chakraborty, R. Ramakrishnan

{"title":"Critical Benchmarking of the G4(MP2) Model, the Correlation Consistent Composite Approach and Popular Density Functional Approximations on a Probabilistically Pruned Benchmark Dataset of Formation Enthalpies","authors":"Sambit Das, S. Chakraborty, R. Ramakrishnan","doi":"10.26434/chemrxiv.12647033.v1","DOIUrl":"https://doi.org/10.26434/chemrxiv.12647033.v1","url":null,"abstract":"First-principles calculation of the standard formation enthalpy, $Delta H_f^0$~(298K), in such large scale as required by chemical space explorations, is amenable only with density functional approximations (DFAs) and some composite wave function theories (cWFTs). Alas, the accuracies of popular range-separated hybrid, `rung-4' DFAs, and cWFTs that offer the best accuracy-vs.-cost trade-off have as yet been established only for datasets predominantly comprising small molecules, hence, their transferability to larger datasets remains vague. In this study, we present an extended benchmark dataset of over two-thousand values of $Delta H_f^0$ for structurally and electronically diverse molecules. We apply quartile-ranking based on boundary-corrected kernel density estimation to filter outliers and arrive at Probabilistically Pruned Enthalpies of 1908 compounds (PPE1908). For this dataset, we rank the prediction accuracies of G4(MP2), ccCA and 23 popular DFAs using conventional and probabilistic error metrics. We discuss systematic prediction errors and highlight the role an empirical higher-level correction (HLC) plays in the G4(MP2) model. Furthermore, we comment on uncertainties associated with the reference empirical data for atoms and systematic errors introduced by these that grow with the molecular size. We believe these findings to aid in identifying meaningful application domains for quantum thermochemical methods.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82623445","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}

引用次数: 0

Potential-energy curve for the a3Σu+ state of a lithium dimer with Slater-type orbitals 具有slater型轨道的锂二聚体a3Σu+态的势能曲线

arXiv: Chemical Physics Pub Date : 2020-06-29 DOI: 10.1103/physreva.102.062806

M. Lesiuk, M. Musiał, R. Moszynski

{"title":"Potential-energy curve for the \u0000a3Σu+\u0000 state of a lithium dimer with Slater-type orbitals","authors":"M. Lesiuk, M. Musiał, R. Moszynski","doi":"10.1103/physreva.102.062806","DOIUrl":"https://doi.org/10.1103/physreva.102.062806","url":null,"abstract":"We report state-of-the-art ab initio calculations of the potential energy curve for the $a^3Sigma_u^+$ state of the lithium dimer conducted to achieve spectroscopic accuracy ($<$1cm$^{-1}$) without any prior adjustment to fit the corresponding experimental data. The nonrelativistic clamped-nuclei component of the interaction energy is calculated with a composite method involving six-electron coupled cluster and full configuration interaction theories combined with basis sets of Slater-type orbitals ranging in quality from double- to sextuple-zeta. To go beyond the nonrelativistic Born-Oppenheimer picture we include both the leading-order relativistic and adiabatic corrections, and find both of these effects to be non-negligible within the present accuracy standards. The potential energy curve developed by us allowed to calculate molecular parameters ($D_e$, $D_0$, $omega_e$ etc.) for this system, as well as the corresponding vibrational energy levels, with an error of only a few tenths of a wavenumber ($0.2-0.4,$cm$^{-1}$). We also report an ab initio value for the scattering length of two $^2S$ lithium atoms which determines the stability of the related Bose-Einstein condensate.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84525067","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}

引用次数: 2

Revealing a full quantum ladder by nonlinear spectroscopy 用非线性光谱学揭示全量子阶梯

arXiv: Chemical Physics Pub Date : 2020-06-24 DOI: 10.3952/physics.v60i3.4302

D. Abramavičius

引用次数: 4

Enhanced optical nonlinearities under collective strong light-matter coupling 集体强光-物质耦合下增强的光学非线性

arXiv: Chemical Physics Pub Date : 2020-06-15 DOI: 10.1103/PhysRevA.103.063111

R. Ribeiro, Jorge A. Campos-Gonzalez-Angulo, N. Giebink, Wei Xiong, J. Yuen-Zhou

{"title":"Enhanced optical nonlinearities under collective strong light-matter coupling","authors":"R. Ribeiro, Jorge A. Campos-Gonzalez-Angulo, N. Giebink, Wei Xiong, J. Yuen-Zhou","doi":"10.1103/PhysRevA.103.063111","DOIUrl":"https://doi.org/10.1103/PhysRevA.103.063111","url":null,"abstract":"Optical microcavities and metallic nanostructures have been shown to significantly modulate the dynamics and spectroscopic response of molecular systems. We present a study of the nonlinear optics of a model consisting of $N$ anharmonic multilevel systems (e.g., Morse oscillators) undergoing collective strong coupling with a resonant infrared microcavity. We find that, under experimentally accessible conditions, molecular systems in microcavities may have nonlinear phenomena significantly intensified due to the high quality of polariton resonances and the enhanced microcavity electromagnetic energy density relative to free space. Particularly large enhancement of multiphoton absorption happens when multipolariton states are resonant with bare molecule multiphoton transitions. In particular, our model predicts two-photon absorption cross section enhancements by several orders of magnitude relative to free space when the Rabi splitting $Omega_R$ is approximately equal to the molecular anharmonic shift $2Delta$. Our results provide rough upper bounds to resonant nonlinear response enhancement factors as relaxation to dark states is treated phenomenologically. Notably, ensembles of two-level systems undergoing strong coupling with a cavity (described by the Tavis-Cummings model) show no such optical nonlinearity enhancements, highlighting the rich phenomenology afforded by multilevel anharmonic systems. Similar conclusions are expected to hold for excitonic systems that share features with our model (e.g., molecular dyes with accessible S_0 -> S_1 -> S_2 transitions) and strongly interact with a UV-visible cavity.","PeriodicalId":8439,"journal":{"name":"arXiv: Chemical Physics","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2020-06-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86215242","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}

引用次数: 16

Analytic First and Second Derivatives for the Fragment Molecular Orbital Method Combined with Molecular Mechanics 结合分子力学的碎片分子轨道法解析一阶导数和二阶导数

arXiv: Chemical Physics Pub Date : 2020-05-18 DOI: 10.22541/au.158985728.81035863

H. Nakata, D. Fedorov

引用次数: 1