Density-matrix based Extended Lagrangian Born-Oppenheimer Molecular Dynamics release_2tc3gwurgvapfglz7vzxqytgue

by Anders M. N. Niklasson

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2020  

Abstract

Extended Lagrangian Born-Oppenheimer molecular dynamics [Phys. Rev. Lett. vol. 100, 123004 (2008)] is presented for Hartree-Fock theory, where the extended electronic degrees of freedom are represented by a density matrix that accounts for fractional occupation numbers at elevated electronic temperatures. A 4th-order metric tensor, T = K'K, is used in the generalized extended harmonic oscillator of the Lagrangian that generates the dynamics of the electronic degrees of freedom. The kernel, K, is given in terms of an inverse Jacobian of a matrix residual function and appears in the equation of motion for the extended harmonic oscillator. A tunable low-rank approximation of this 4th-order kernel is used for the integration of the electronic degrees of freedom. In contrast to regular direct Born-Oppenheimer molecular dynamics simulations, no iterative self-consistent field optimization is required prior to the force evaluations. The formulation and algorithms provide a general guide to implement extended Lagrangian Born-Oppenheimer molecular dynamics for quantum chemistry, density functional theory, and semiempirical methods using a density matrix formalism.
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Date   2020-03-19
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Number  LA-UR-20-22452
arXiv  2003.09050v1
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