First principles molecular dynamics without self-consistent field optimization

Abstract

We present a first principles molecular dynamics approach that is based on time-reversible extended Lagrangian Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] in the limit of vanishing self-consistent field optimization. The optimization-free dynamics keeps the computational cost to a minimum and typically provides molecular trajectories that closely follow the exact Born-Oppenheimer potential energy surface. Only one single diagonalization and Hamiltonian (or Fockian) construction are required in each integration time step. The proposed dynamics is derived for a general free-energy potential surface valid at finite electronic temperatures within hybrid density functional theory. Even in the event of irregular functional behavior that may cause a dynamical instability, the optimization-free limit represents a natural starting guess for force calculations that may require a more elaborate iterative electronic ground state optimization. Our optimization-free dynamics thus represents a flexible theoretical framework for a broad and general class of ab initio molecular dynamics simulations.

Generalized extended Lagrangian Born-Oppenheimer molecular dynamics

“…It is easy to see that previous formulations of extended Lagrangian Born-Oppenheimer molecular dynamics in the limit of vanishing self-consistent field optimization [17,23,24] are recovered with a scaled δ-function approximation of the kernel, i.e. for K(r, r ′ ) = −c δ(r − r ′ ) in Eq.…”

Linear-scaling first-principles molecular dynamics of complex biological systems with the Conquest code

“…With this method, the time reversibility of the electronic structure is maintained and the stability of the BOMD simulations is greatly improved. 6,31,32) Recently, we have combined this XL-BOMD scheme with the DMM method and demonstrated that the combined method enables us to perform efficient and reliable FPMD simulations with the OðNÞ method. 7) The Lagrangian in the XL-BOMD scheme L XBO is defined as follows, using the Lagrangian in the usual BOMD method L BO ,…”

Graph-based linear scaling electronic structure theory

“…Figure 5 shows the fluctuations of the total energy during a microcanonical molecular dynamics simulation of liquid water that was performed using LATTE 58 and the extended Lagrangian formulation of Born-Oppenheimer molecular dynamics. 50,[67][68][69][70] The density matrix was calculated from a partitioning over separate subgraphs of S τ (t), with one water molecule per core. For the Fermi-operator expansion (at zero temperature) we used the recursive SP2 algorithm.…”