Quantum Monte Carlo calculation of the binding energy of the beryllium dimer

Journal Article · Fri Aug 28 04:00:00 EDT 2015 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4929351· OSTI ID:22493567

Deible, Michael J.; Kessler, Melody; Gasperich, Kevin E.; Jordan, Kenneth D. ^[1]

---

1. Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)

The accurate calculation of the binding energy of the beryllium dimer is a challenging theoretical problem. In this study, the binding energy of Be{sub 2} is calculated using the diffusion Monte Carlo (DMC) method, using single Slater determinant and multiconfigurational trial functions. DMC calculations using single-determinant trial wave functions of orbitals obtained from density functional theory calculations overestimate the binding energy, while DMC calculations using Hartree-Fock or CAS(4,8), complete active space trial functions significantly underestimate the binding energy. In order to obtain an accurate value of the binding energy of Be{sub 2} from DMC calculations, it is necessary to employ trial functions that include excitations outside the valence space. Our best estimate DMC result for the binding energy of Be{sub 2}, obtained by using configuration interaction trial functions and extrapolating in the threshold for the configurations retained in the trial function, is 908 cm{sup −1}, only slightly below the 935 cm{sup −1} value derived from experiment.

• OSTI ID: 22493567
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 8 Vol. 143; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
BERYLLIUM
BINDING ENERGY
CONFIGURATION INTERACTION
DENSITY FUNCTIONAL METHOD
DIFFUSION
DIMERS
HARTREE-FOCK METHOD
MONTE CARLO METHOD
SLATER METHOD
SPACE
VALENCE