NQCDynamics.jl: A Julia package for nonadiabatic quantum classical molecular dynamics in the condensed phase

Abstract

Accurate and efficient methods to simulate nonadiabatic and quantum nuclear effects in high-dimensional and dissipative systems are crucial for the prediction of chemical dynamics in condensed phase. To facilitate effective development, code sharing and uptake of newly developed dynamics methods, it is important that software implementations can be easily accessed and built upon.Using the Julia programming language, we have developed the \pkgname ~ package which provides a framework for established and emerging methods for performing semiclassical and mixed quantum-classical dynamics in condensed phase. The code provides several interfaces to existing atomistic simulation frameworks, electronic structure codes, and machine learning representations. In addition to the existing methods, the package provides infrastructure for developing and deploying new dynamics methods which we hope will benefit reproducibility and code sharing in the field of condensed phase quantum dynamics. Herein, we present our code design choices and the specific Julia programming features from which they benefit.We further demonstrate the capabilities of the package on two examples of chemical dynamics in condensed phase: the population dynamics of the spin-boson model as described by a wide variety of semi-classical and mixed quantum-classical nonadiabatic methods and the reactive scattering of H2 on Ag(111) using the Molecular Dynamics with Electronic Friction method. Together, they exemplify the broad scope of the package to study effective model Hamiltonians and realistic atomistic systems.

Efficient implementation and performance analysis of the independent electron surface hopping method for dynamics at metal surfaces

“…We have implemented the IESH algorithm in the open-source software package NQCDynamics.jl. 33 Since IESH demonstrates algorithmic similarity with other TSH methods, for example like fewest-switches surface hopping it also requires velocity rescaling upon a successful hop, it has been implemented by reusing and extending the existing TSH functionality. The algorithm proceeds via numerical integration of the coupled differential equations of motion for the nuclear and electronic subsystems, along with execution of a callback function at every time step that performs the surface hopping procedure.…”

“…30 The increasing popularity of machine learning techniques may prove beneficial in this area, similar to recent progress accelerating MDEF simulations. 31,32 In this article, we present a reliable and efficient implementation of IESH, available in the recently-announced open-source NQCDynamics.jl package, 33 and demonstrate its application to a variety of systems. We provide a detailed description of the implementation and present solutions to challenges encountered along the way.…”

“…This is facilitated by the NQCModels.jl framework previously introduced as part of NQCDynamics.jl. 33 Although a number of popular software solutions exist for TSH methods, [35][36][37] these do not currently treat metallic systems using IESH. When benchmarking IESH with one dimensional models, it has been previously compared to Marcus theory 11,13 but not a numerically exact method such as the HQME.…”

Newton-X Platform: New Software Developments for Surface Hopping and Nuclear Ensembles

“…(A few earlier surface hopping codes were available, like those implemented in ANT, CPMD, or MOPAC − each excelling in specific niches. Newton-X remains relevant by providing a complete set of tools for all steps of the nonadiabatic dynamics research, from spectrum simulations to advanced data analysis.…”

The Newton-X platform: new software developments for surface hopping and nuclear ensembles

“…When Newton-X was first released in 2007, it was the only publicly available software for surface hopping and nuclear ensembles using ab initio quantum-chemical methods. Since then, many other options have appeared, [7][8][9][10][11][12][13][14][15][16][17] each excelling in specific niches. Newton-X remains relevant by providing a complete set of tools for all steps of the nonadiabatic dynamics research, from spectrum simulations to advanced data analysis.…”