How Important is Orbital Choice in Single-Determinant Diffusion Quantum Monte Carlo Calculations?

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• 作者：Manolo C. Per ; Kelly A. Walker ; Salvy P. Russo
• 刊名：Journal of Chemical Theory and Computation
• 出版年：2012
• 出版时间：July 10, 2012
• 年：2012
• 卷：8
• 期：7
• 页码：2255-2259
• 全文大小：223K
• 年卷期：v.8,no.7(July 10, 2012)
• ISSN：1549-9626

文摘

The accuracy of total electronic energies obtained using the fixed-node diffusion quantum Monte Carlo (FN-DMC) method is determined by the choice of the many-body nodal surface. Here, we perform a systematic comparison of the quality of FN-DMC energies for a selection of atoms and diatomic molecules using nodal surfaces defined by single determinants of Hartree鈥揊ock, B3LYP, and LDA orbitals. Through comparison with experimental results, we show that the use of Kohn鈥揝ham orbitals results in significantly improved FN-DMC atomization energies over those obtained using Hartree鈥揊ock orbitals. We also discuss the effect of spin contamination in the orbitals.