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arXiv · 1603.07336

Auxiliary-field quantum Monte Carlo calculations of the molybdenum dimer

Wirawan Purwanto·Shiwei Zhang·Henry Krakauer
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Abstract

Chemical accuracy is difficult to achieve for systems with transition metal atoms. Third row transition metal atoms are particularly challenging due to strong electron-electron correlation in localized d-orbitals. The Cr2 molecule is an outstanding example, which we previously treated with highly accurate auxiliary-field quantum Monte Carlo (AFQMC) calculations [Purwanto et al., J. Chem. Phys. 142, 064302 (2015)]. Somewhat surprisingly, computational description of the isoelectronic Mo2 dimer has also, to date, been scattered and less than satisfactory. We present high-level theoretical benchmarks of the Mo2 singlet ground state ($X ^1Σ_g^+$) and first triplet excited state ($a ^3Σ_u^+$), using the phaseless AFQMC calculations. Extrapolation to the complete basis set limit is performed. Excellent agreement with experimental spectroscopic constants is obtained. We also present a comparison of the correlation effects in Cr2 and Mo2.

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Wirawan Purwanto, Shiwei Zhang, Henry Krakauer. 2016-03-23. Auxiliary-field quantum Monte Carlo calculations of the molybdenum dimer. https://doi.org/10.1063/1.4954245

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