Electronic Quantum Monte Carlo Calculations of Atomic Forces, Vibrations, and Anharmonicities

Abstract

Atomic forces are calculated for first-row monohydrides and carbon monoxide within electronic quantum Monte Carlo (QMC). Accurate and efficient forces are achieved by using an improved method for moving variational parameters in variational QMC. Newton's method with singular value decomposition (SVD) is combined with steepest descent (SD) updates along directions rejected by the SVD, after initial SD steps. Dissociation energies in variational and diffusion QMC agree well with experiment. The atomic forces agree quantitatively with potential energy surfaces, demonstrating the accuracy of this force procedure. The harmonic vibrational frequencies and anharmonicity constants, derived from the QMC energies and atomic forces, also agree well with experimental values.

6 pages, 2 figures; updated content

References in corpus (4)

• Zero-Variance Zero-Bias Principle for Observables in quantum Monte Carlo: Application to Forces
• Correlated sampling in quantum Monte Carlo: a route to forces
• Optimization of Quantum Monte Carlo Wave Functions Using Analytical Energy Derivatives
• Accurate, efficient and simple forces with Quantum Monte Carlo methods

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• Complementary First and Second Derivative Methods for Ansatz Optimization in Variational Monte Carlo
• Towards Quantum Monte Carlo Forces on Heavier Ions: Scaling Properties
• A simple and efficient approach to the optimization of correlated wave functions
• How Large are Nonadiabatic Effects in Atomic and Diatomic Systems?
• Implementation of the Linear Method for the optimization of Jastrow-Feenberg and Backflow Correlations
• Optimisation of quantum Monte Carlo wave function: steepest descent method