Article (Scientific journals)
Perturbed path integrals in imaginary time: Efficiently modeling nuclear quantum effects in molecules and materials
Poltavskyi, Igor; DiStasio, Robert; Tkatchenko, Alexandre
2018In Journal of Chemical Physics, 148 (10), p. 102325
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Keywords :
imaginary time path integrals; ab initio simulations; nuclear quantum effects
Abstract :
[en] Nuclear quantum effects (NQE), which include both zero-point motion and tunneling, exhibit quite an impressive range of influence over the equilibrium and dynamical properties of molecules and materials. In this work, we extend our recently proposed perturbed path-integral (PPI) approach for modeling NQE in molecular systems [I. Poltavsky and A. Tkatchenko, Chem. Sci. 7, 1368 (2016)], which successfully combines the advantages of thermodynamic perturbation theory with path-integral molecular dynamics (PIMD), in a number of important directions. First, we demonstrate the accuracy, performance, and general applicability of the PPI approach to both molecules and extended (condensed-phase) materials. Second, we derive a series of estimators within the PPI approach to enable calculations of structural properties such as radial distribution functions (RDFs) that exhibit rapid convergence with respect to the number of beads in the PIMD simulation. Finally, we introduce an effective nuclear temperature formalism within the framework of the PPI approach and demonstrate that such effective temperatures can be an extremely useful tool in quantitatively estimating the “quantumness” associated with different degrees of freedom in the system as well as providing a reliable quantitative assessment of the convergence of PIMD simulations. Since the PPI approach only requires the use of standard second-order imaginary-time PIMD simulations, these developments enable one to include a treatment of NQE in equilibrium thermodynamic properties (such as energies, heat capacities, and RDFs) with the accuracy of higher-order methods but at a fraction of the computational cost, thereby enabling first-principles modeling that simultaneously accounts for the quantum mechanical nature of both electrons and nuclei in large-scale molecules and materials.
Disciplines :
Physics
Author, co-author :
Poltavskyi, Igor ;  University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit
DiStasio, Robert;  Cornell University, Ithaca, NY 14853, United States > Department of Chemistry & Chemical Biology
Tkatchenko, Alexandre ;  University of Luxembourg > Faculty of Science, Technology and Communication (FSTC) > Physics and Materials Science Research Unit
External co-authors :
yes
Language :
English
Title :
Perturbed path integrals in imaginary time: Efficiently modeling nuclear quantum effects in molecules and materials
Publication date :
14 March 2018
Journal title :
Journal of Chemical Physics
ISSN :
1089-7690
Publisher :
American Institute of Physics
Special issue title :
NUCLEAR QUANTUM EFFECTS
Volume :
148
Issue :
10
Pages :
102325
Peer reviewed :
Peer Reviewed verified by ORBi
Focus Area :
Computational Sciences
FnR Project :
FNR11360857 - Quantum Ion Tunneling And Scattering In Layered Nanomaterials, 2016 (01/03/2017-28/02/2020) - Alexandre Tkatchenko
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