Direct evaluation of the force constant matrix in quantum Monte Carlo.
The Journal of chemical physics
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Liu, Y. Y. F., Andrews, B., & Conduit, G. (2019). Direct evaluation of the force constant matrix in quantum Monte Carlo.. The Journal of chemical physics, 150 (3), 034104. https://doi.org/10.1063/1.5070138
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 PBE functional and comparable or better than density functional theory with a semi-empirical functional.
Royal Society (uf130122)
External DOI: https://doi.org/10.1063/1.5070138
This record's URL: https://www.repository.cam.ac.uk/handle/1810/288796