How large are nonadiabatic effects in atomic and diatomic systems?
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Details
| Original language | English |
|---|---|
| Article number | 124308 |
| Journal | Journal of Chemical Physics |
| Volume | 143 |
| Issue number | 12 |
| DOIs | |
| Publication status | Published - Sep 2015 |
| Publication type | A1 Journal article-refereed |
Abstract
With recent developments in simulating nonadiabatic systems to high accuracy, it has become possible to determine how much energy is attributed to nuclear quantum effects beyond zero-point energy. In this work, we calculate the non-relativistic ground-state energies of atomic and molecular systems without the Born-Oppenheimer approximation. For this purpose, we utilize the fixed-node diffusion Monte Carlo method, in which the nodes depend on both the electronic and ionic positions. We report ground-state energies for all systems studied, ionization energies for the first-row atoms and atomization energies for the first-row hydrides. We find the ionization energies of the atoms to be nearly independent of the Born-Oppenheimer approximation, within the accuracy of our results. The atomization energies of molecular systems, however, show small effects of the nonadiabatic coupling between electrons and nuclei.