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It was shown recently that smooth and continuous "Matsubara" phase-space loops follow a quantum-Boltzmann-conserving classical dynamics when decoupled from non-smooth distributions, which was suggested as the reason that many dynamical…

Chemical Physics · Physics 2018-07-06 George Trenins , Stuart C. Althorpe

Classical and path integral molecular dynamics (PIMD) simulations are used to study alpha-quartz and beta-quartz in a large range of temperatures at zero external stress. PIMD account for quantum fluctuations of atomic vibrations, which can…

Materials Science · Physics 2015-06-24 Martin H. Muser

Two-dimensional Raman and hybrid terahertz/Raman spectroscopic techniques provide invaluable insight into molecular structure and dynamics of condensed-phase systems. However, corroborating experimental results with theory is difficult due…

Chemical Physics · Physics 2022-04-13 Tomislav Begušić , Xuecheng Tao , Geoffrey A. Blake , Thomas F. Miller

An exact approach to compute physical properties for general multi-electronic-state (MES) systems in thermal equilibrium is presented. The approach is extended from our recent progress on path integral molecular dynamics (PIMD) [J. Chem.…

Chemical Physics · Physics 2017-11-22 Xinzijian Liu , Jian Liu

We expand iterative numerically-exact influence functional path-integral tools and present a method capable of following the nonequilibrium time evolution of subsystems coupled to multiple bosonic and fermionic reservoirs simultaneously.…

Mesoscale and Nanoscale Physics · Physics 2015-06-15 Lena Simine , Dvira Segal

Conventional molecular dynamics simulations macromolecules require long computational times because the most interesting motions are very slow compared with the fast oscillations of bond lengths and bond angles that limit the integration…

Chemical Physics · Physics 2008-02-03 Alexey K. Mazur

We present a numerical path-integral iteration scheme for the low dimensional reduced density matrix of a time-dependent quantum dissipative system. Our approach simultaneously accounts for the combined action of a microscopically modelled…

Quantum Physics · Physics 2016-10-12 A. M. Barth , A. Vagov , V. M. Axt

We introduce sbml4md, a newly developed algorithm implemented as a software package to extract parameters of multimode anharmonic Brownian (MAB) models from molecular dynamics (MD) trajectories for simulating nonlinear vibrational spectra…

Chemical Physics · Physics 2026-03-20 Kwanghee Park , Seiji Ueno , Yoshitaka Tanimura

Ab initio molecular dynamics (AIMD) is a powerful tool to predict properties of molecular and condensed matter systems. The quality of this procedure is based on accurate electronic structure calculations. The development of quantum…

Matsubara dynamics is the classical dynamics which results when imaginary-time path-integrals are smoothed; it conserves the quantum Boltzmann distribution and appears in drastically approximated form in path-integral dynamics methods such…

Chemical Physics · Physics 2026-05-05 Adam Prada , Eszter S. Pós , Stuart C. Althorpe

Strong coupling between a system and its environment leads to the emergence of non-Markovian dynamics, which cannot be described by a time-local master equation. One way to capture such dynamics is to use numerical real-time path integrals,…

Mesoscale and Nanoscale Physics · Physics 2017-11-29 Aidan Strathearn , Brendon W. Lovett , Peter Kirton

The path integral approach offers not only an exact expression for the non- equilibrium dynamics of dissipative quantum systems, but is also a convenient starting point for perturbative treatments. An alternative way to explore the…

Statistical Mechanics · Physics 2022-09-21 Joachim Ankerhold

We introduce a novel simple algorithm for thermostatting path integral molecular dynamics (PIMD) with the Langevin equation. The staging transformation of path integral beads is employed for demonstration. The optimum friction coefficients…

Statistical Mechanics · Physics 2017-10-17 Jian Liu , Dezhang Li , Xinzijian Liu

Molecules like water have vibrational modes with a zero-point energy well above room temperature. As a consequence, classical molecular dynamics simulations of their liquids largely underestimate the energy of modes with a higher zero-point…

Statistical Mechanics · Physics 2013-05-08 Sriram Ganeshan , Rafael Ramírez , M. V. Fernández-Serra

Stochastic Schr{\"o}dinger equations for quantum trajectories offer an alternative and sometimes superior approach to the study of open quantum system dynamics. Here we show that recently established convolutionless non-Markovian stochastic…

Quantum Physics · Physics 2009-11-10 Walter T. Strunz , Ting Yu

Thermal quantum time-correlation functions are of fundamental importance in quantum dynamics, allowing experimentally-measurable properties such as reaction rates, diffusion constants and vibrational spectra to be computed from first…

Chemical Physics · Physics 2017-07-25 Timothy J. H. Hele

This manuscript aims to illustrate a quantum-classical dissipative theory (suited to be converted to effective algorithms for numerical simulations) within the long-term project of studying molecular processes in the brain. Other…

Neurons and Cognition · Quantitative Biology 2025-03-04 Alessandro Sergi , Antonino Messina , Rosalba Saija , Gabriella Martino , Maria Teresa Caccamo , Min-Fang Kuo , Michael A. Nitsche

Ab initio Born-Oppenheimer molecular dynamics (AIMD) is a valuable method for simulating physico-chemical processes of complex systems, including reactive systems, and for training machine learning models and force fields. Speed and…

An exact real time quantum dynamics preaveraged over imaginary time path integral is formulated for general condensed phase equilibrium ensemble. This formulation results in the well-known centroid dynamics approach upon filtering of…

Quantum Physics · Physics 2014-02-11 Seogjoo Jang

Recent developments in path integral methodology have significantly reduced the computational expense of including quantum mechanical effects in the nuclear motion in ab initio molecular dynamics simulations. However, the implementation of…

Computational Physics · Physics 2014-02-06 Michele Ceriotti , Joshua More , David E. Manolopoulos