Force correcting atom centred potentials for generalised gradient approximated density functional theory: Approaching hybrid functional accuracy for geometries and harmonic frequencies in small chlorofluorocarbons

Abstract

Generalised gradient approximated (GGA) density functional theory (DFT) typically overestimates polarisability and bond-lengths, and underestimates force constants of covalent bonds. To overcome this problem we show that one can use empirical force correcting atom centred potentials (FCACPs), parametrised for every nuclear species. Parameters are obtained through minimisation of a penalty functional that explicitly encodes hybrid DFT forces and static polarisabilities of reference molecules. For hydrogen, fluorine, chlorine and carbon the respective reference molecules consist of H₂, F₂, Cl₂ and CH₄. The transferability of this approach is assessed for harmonic frequencies in a small set of chlorofluorocarbon molecules. Numerical evidence, gathered for CF₄, CCl₄, CCl₃F, CCl₂F₂, CClF₃, ClF, HF, HCl, CFH₃, CF₂H₂, CF₃H, CHCl₃, CH₂Cl₂ and CH₃Cl indicates that the GGA+FCACP level of theory yields harmonic frequencies that are significantly more consistent with hybrid DFT values, as well as slightly reduced molecular polarisability.

Keywords:

• vibrational spectroscopy
• atom centered potentials
• plane-wave and pseudopotentials
• high-performance computing

Acknowledgements

This article is dedicated to Prof. M. Quack, the author’s Diplomvater at ETH Zürich in 2001, and co-author of the resulting paper [14]. The author is thankful for many technical discussions with P.J. Feibelman, A.E. Mattsson and A.G. Taube at Sandia National Laboratories. This research used resources of the Argonne Leadership Computing Facility at Argonne National Laboratory, which is supported by the Office of Science of the U.S. DOE under contract DE-AC02-06CH11357.

Notes

^a4401.2; ^b916.9; ^c559.7; ^d3019.0, 2917, 1534.0, 1306.0.

^a4138.4; ^b2990.9;^c738.5; ^d776.0, 459.0, 314.0, 217.0; ^e1280.0, 909.0, 631.0, 453.0; ^f1085.0, 847.0, 535.0, 394.0, 350.0, 241.0; ^g3034.1, 1219.7, 774.0, 680.0, 366.0, 260.0; ^h3006.0, 2930.0, 1467.0, 1464.0, 1182.0, 1049.0; ⁱ1212.0, 1105.0, 781.0, 563.0, 476.0, 350.0; ^j3041.8, 2966.2, 1454.6, 1354.9, 1015.0, 732.1; ^k3036.0, 1372.0, 1152.0, 1117.0, 700.0, 507.0; ^l1159.0, 1101.0, 902.0, 667.0, 458.0, 446.0, 437.0, 322.0, 262.0; ^m3040.0, 2999.0, 1467.0, 1268.0, 1153.0, 898.0, 758.0, 717.0, 282.0, ⁿ3014.0, 2948.0, 1508.0, 1435.0, 1262.0, 1178.3, 1111.2, 1090.1, 528.5.