Direct Quantum Dynamics Using Grid-Based Wave Function Propagation and Machine-Learned Potential Energy Surfaces

doi:10.1021/acs.jctc.7b00507

2017-08-01

Gareth W. Richings

Scott Habershon *

DOI：10.1021/acs.jctc.7b00507

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摘要

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We describe a method for performing nuclear quantum dynamics calculations using standard, grid-based algorithms, including the multiconfiguration time-dependent Hartree (MCTDH) method, where the potential energy surface (PES) is calculated on-the-fly. The method of Gaussian process regression (GPR) is used to construct a global representation of the PES using values of the energy at points distributed in molecular configuration space during the course of the wavepacket propagation. We demonstrate this direct dynamics approach for both an analytical PES function describing 3-dimensional proton transfer dynamics in malonaldehyde and for 2- and 6-dimensional quantum dynamics simulations of proton transfer in salicylaldimine. In the case of salicylaldimine we also perform calculations in which the PES is constructed using Hartree-Fock calculations through an interface to an ab initio electronic structure code. In all cases, the results of the quantum dynamics simulations are in excellent agreement with previous simulations of both systems yet do not require prior fitting of a PES at any stage. Our approach (implemented in a development version of the Quantics package) opens a route to performing accurate quantum dynamics simulations via wave function propagation of many-dimensional molecular systems in a direct and efficient manner.

Keyword:

DIMENSIONAL MODEL REPRESENTATIONS

GAUSSIAN PROCESS REGRESSION

INITIO MOLECULAR-DYNAMICS

DEPENDENT HARTREE THEORY

EXCITED-STATE DYNAMICS

NONADIABATIC DYNAMICS

CONICAL INTERSECTION

MMVB DYNAMICS

PHOTOCHEMISTRY

WAVEPACKETS