Monte Carlo configuration interaction applied to multipole moments, ionisation energies and electron affinities

Abstract

The method of Monte Carlo configuration interaction (MCCI) [1,2] is applied to the calculation of multipole moments. We look at the ground and excited state dipole moments in carbon monoxide. We then consider the dipole of NO, the quadrupole of the nitrogen molecule and of BH. An octupole of methane is also calculated. We consider experimental geometries and also stretched bonds. We show that these non-variational quantities may be found to relatively good accuracy when compared with FCI results, yet using only a small fraction of the full configuration interaction space. MCCI results in the aug-cc-pVDZ basis are seen to generally have reasonably good agreement with experiment. We also investigate the performance of MCCI when applied to ionisation energies and electron affinities of atoms in an aug-cc-pVQZ basis. We compare the MCCI results with full configuration-interaction quantum Monte Carlo [3,4] and `exact' non-relativistic results [3,4]. We show that MCCI could be a useful alternative for the calculation of atomic ionisation energies however electron affinities appear much more challenging for MCCI. Due to the small magnitude of the electron affinities their percentage errors can be high, but with regards to absolute errors MCCI performs similarly for ionisation energies and electron affinities.

12 pages, 20 figures

References in corpus (2)

• Comment on: "Estimating the Hartree-Fock limit from finite basis set calculations" [Jensen F (2005) Theor Chem Acc 113:267]
• Calculations of Potential Energy Surfaces Using Monte Carlo Configuration Interaction

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• State-averaged Monte Carlo configuration interaction applied to electronically excited states
• Approaching exact hyperpolarizabilities via sum-over-states Monte Carlo configuration interaction
• Ground- and Excited-State Dipole Moments and Oscillator Strengths of Full Configuration Interaction Quality
• Multireference X-Ray Emission and Absorption Spectroscopy calculations from Monte Carlo Configuration Interaction
• Molecular electric moments calculated by using natural orbital functional theory
• Characterizing a configuration interaction excited state using natural transition geminals
• Electronic energies from coupled fermionic 'Zombie' states imaginary time evolution