Calculations of Potential Energy Surfaces Using Monte Carlo Configuration Interaction

Abstract

We apply the method of Monte Carlo configuration interaction (MCCI) to calculate ground-state potential energy curves for a range of small molecules and compare the results with full configuration interaction. We show that the MCCI potential energy curve can be calculated to relatively good accuracy, as quantified using the non-parallelity error, using only a very small fraction of the FCI space. In most cases the potential curve is of better accuracy than its constituent single-point energies. We finally test the MCCI program on systems with basis sets beyond full configuration interaction: a lattice of fifty hydrogen atoms and ethylene. The results for ethylene agree fairly well with other computational work while for the lattice of fifty hydrogens we find that the fraction of the full configuration interaction space we were able to consider appears to be too small as, although some qualitative features are reproduced, the potential curve is less accurate.

14 pages, 22 figures

References in corpus (2)

• Multireference Correlation in Long Molecules with the Quadratic Scaling Density Matrix Renormalization Group
• Construction of CASCI-type wave functions for very large active spaces

Cited by in corpus (6)

• Adaptive multiconfigurational wave functions
• Applying Monte Carlo configuration interaction to transition metal dimers: exploring the balance between static and dynamic correlation
• Development of Monte Carlo configuration interaction: Natural orbitals and second-order perturbation theory
• Approaching exact hyperpolarizabilities via sum-over-states Monte Carlo configuration interaction
• Multireference X-Ray Emission and Absorption Spectroscopy calculations from Monte Carlo Configuration Interaction
• Monte Carlo configuration interaction applied to multipole moments, ionisation energies and electron affinities