Assessment of two hybrid van der Waals density functionals for covalent and non-covalent binding of molecules
[2];
[2]
- Univ. of Oslo, Oslo (Norway). Centre for Materials Science and Nanotechnology (SMN), Dept. of Physics
- Chalmers Univ. of Technology, Gothenburg (Sweden). Microtechnology and Nanoscience–MC2
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Foundry; Univ. of California, Berkeley, CA (United States). Dept. of Physics
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Foundry; Univ. of California, Berkeley, CA (United States). Dept. of Physics; Kavli Energy NanoScience Inst. at Berkeley, Berkeley, CA (United States)
Two hybrid van der Waals density functionals (vdW-DFs) are developed using 25% Fock exchange with (i) the consistent-exchange vdW-DF-cx functional [K. Berland and P. Hyldgaard, Phys. Rev. B 89, 035412 (2014)] and (ii) with the vdW-DF2 functional [K. Lee et al., Phys. Rev. B 82, 081101 (2010)]. The ability to describe covalent and non-covalent binding properties of molecules is assessed. For properties related to covalent binding, atomization energies (G2-1 set), molecular reaction energies (G2RC set), and ionization energies (G21IP set) are benchmarked against experimental reference values. We find that hybrid-vdW-DF-cx yields results that are rather similar to those of the standard non-empirical hybrid PBE0 [C. Adamo and V. Barone, J. Chem. Phys. 110, 6158 (1999)], with mean average deviations (MADs) of 4.9 and 5.0 kcal/mol for the G2-1 set, respectively. In this comparison, experimental reference values are used, back corrected by wavefunction-based quantum-chemistry calculations of zero-point energies. Hybrid vdW-DF2 follows somewhat different trends, showing on average significantly larger deviations from the reference energies, with a MAD of 14.5 kcal/mol for the G2-1 set. Non-covalent binding properties of molecules are assessed using the S22 benchmark set of non-covalently bonded dimers and the X40 set of dimers of small halogenated molecules, using wavefunction-based quantum chemistry results as references. For the S22 set, hybrid-vdW-DF-cx performs better than standard vdW-DF-cx for the mostly hydrogen-bonded systems, with MAD dropping from 0.6 to 0.3 kcal/mol, but worse for purely dispersion-bonded systems, with MAD increasing from 0.2 to 0.6 kcal/mol. Hybrid-vdW-DF2 offers a slight improvement over standard vdW-DF2. Similar trends are found for the X40 set, with hybrid-vdW-DF-cx performing particularly well for binding energies involving the strongly polar hydrogen halides, but poorly for systems with tiny binding energies. Our study of the X40 set reveals the potential of mixing Fock exchange with vdW-DF, but also highlights shortcomings of the hybrids constructed here. In conclusion, the solid performance of hybrid-vdW-DF-cx for covalent-bonded systems, as well as the strengths and issues uncovered for non-covalently bonded systems, makes this study a good starting point for developing even more accurate hybrid vdW-DFs.
- Research Organization:
- Univ. of California, Berkeley, CA (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Gas Separations Relevant to Clean Energy Technologies (CGS)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); Swedish Research Council (SRC); Research Council of Norway; Swedish National Infrastructure for Computing (SNIC)
- Grant/Contract Number:
- SC0001015; AC02-05CH11231; 2016-10-12
- OSTI ID:
- 1388990
- Alternate ID(s):
- OSTI ID: 1364666
- Journal Information:
- Journal of Chemical Physics, Vol. 146, Issue 23; Related Information: CGS partners with University of California, Berkeley; University of California, Davis; Lawrence Berkeley National Laboratory; University of Minnesota; National Energy Technology Laboratory; Texas A&M University; ISSN 0021-9606
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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