Novel density functional methodology for the computation of accurate electronic and thermodynamic properties of molecular systems and improved long-range behavior

Journal Article · Thu Dec 10 04:00:00 EST 1998 · Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory

DOI:https://doi.org/10.1021/jp982862g· OSTI ID:320827

Kafafi, S A ^[1]

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1. Univ. of Maryland Biotechnology Inst., Rockville, MD (United States). Center for Advanced Research in Biotechnology

A novel general purpose density functional methodology for the computation of accurate electronic and thermodynamic properties of molecules and improved long-range behavior is reported. Assuming the separability of the exchange (E{sub x}) and correlation (E{sub c}) contributions to the total exchange-correlation energy functional (E{sub xc}), the E{sub x} term consists of a hybrid mixture of 37.5% Hartree-Fock exchange and the appropriate local spin density exchange using the adiabatic connection formula. He demonstrated that E{sub x} and its corresponding potential V{sub x} [=dE{sub x}/d{rho}(r)] have the proper asymptotic limits at r = 0 and r {r_arrow} {infinity}, E{sub c} consists of the Vosko, Wilk, and Nusair formula for the free-electron gas correlation energy and a generalized gradient approximation term with one adjustable parameter. V{sub c} [=dE{sub c}/d{rho}(r)] was shown to obey the r {r_arrow} {infinity} limit of the corresponding potential derived from exact atomic exchange-correlation computations; namely, V{sub c} is proportional to r{sup {minus}4}. Most importantly, he demonstrated that, at r values where dispersion forces are operating, V{sub c} is proportional to 1/r{sup n} (n = 4, 6, 8, {hor_ellipsis}). The reported method was denoted by K2-BVWN because it used two adjustable parameters in its formulation. The K2-BVWN scheme scales as N{sup 3}, where N is the number of basis functions, compared to {approximately}N{sup 7} for Gaussian-2 (G2) ab initio theory and related methods, {approximately}N{sup 5} for Barone`s mPW1,3PW, and {approximately}N{sup 4} for Becke`s three-parameter density functional approaches. The G2 data set complemented by the reported molecular systems investigated in this work was recommended as a critical test for evaluating novel ab initio and density functional methodologies. The K2-BVWN method has been implemented in the Gaussian series of programs.

• Sponsoring Organization: USDOE, Washington, DC (United States)
• OSTI ID: 320827
• Journal Information: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory, Journal Name: Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory Journal Issue: 50 Vol. 102; ISSN 1089-5639; ISSN JPCAFH
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BINDING ENERGY
ELECTRON CORRELATION
ELECTRON EXCHANGE
ELECTRONIC STRUCTURE
ENERGY DENSITY
HARTREE-FOCK METHOD
MOLECULES
QUANTUM MECHANICS
THERMODYNAMIC PROPERTIES