Details

Autor(en) / Beteiligte

• Liu, Y. Y. F.
• Andrews, B.
• Conduit, G. J.

Titel

Direct evaluation of the force constant matrix in quantum Monte Carlo

Ist Teil von

• The Journal of chemical physics, 2019-01, Vol.150 (3), p.034104-034104

Ort / Verlag

United States: American Institute of Physics

Erscheinungsjahr

2019

Quelle

American Institute of Physics (AIP) Journals

Beschreibungen/Notizen

• We develop a formalism to directly evaluate the matrix of force constants within a Quantum Monte Carlo calculation. We utilize the matrix of force constants to accurately relax the positions of atoms in molecules and determine their vibrational modes, using a combination of variational and diffusion Monte Carlo. The computed bond lengths differ by less than 0.007 Å from the experimental results for all four tested molecules. For hydrogen and hydrogen chloride, we obtain fundamental vibrational frequencies within 0.1% of experimental results and ∼10 times more accurate than leading computational methods. For carbon dioxide and methane, the vibrational frequency obtained is on average within 1.1% of the experimental result, which is at least 3 times closer than results using restricted Hartree-Fock and density functional theory with a Perdew-Burke-Ernzerhof functional and comparable or better than density functional theory with a semi-empirical functional.