Density Functional Theory

The density functional theory module in Jaguar allows you to employ a variety of functionals to describe exchange and correlation for either open or closed shell systems. The theory is described in Density Functional Theory. This section describes how to set up a DFT calculation in Jaguar. You can perform DFT geometry optimizations, solvation calculations, charge fitting, and all other calculations and properties available for Hartree-Fock wave functions. For a tutorial exercise involving DFT functionals and basis sets, see Introduction to Geometry Optimizations, Functionals and Basis Sets.

DFT calculations are selected by making a choice with the Theory tools menu in the Input tab, either by setting the default for all structures or by selection for each structure.

The functionals that are recommended for most uses can be selected by filtering to the Recommended set. There are five classes of functionals available:

• hybrid functionals, which include a Hartree-Fock exchange contribution as well as local and nonlocal functionals;
• gradient-corrected pure density functionals, which contain functionals of the gradient of the density and may also contain functionals of the kinetic energy density;
• local density functionals;
• a posteriori corrected functionals, which apply an energy correction after the SCF (for example, for dispersion);
• long-range-corrected functionals, which partition the HF exchange into short-range and long-range parts (see Long-Range-Corrected Density Functionals).

To use other functionals, clear the filter (or use a different filter) and choose the functional from the list.

Many of the hybrid methods employ either the parameters developed for Becke’s three-parameter method [32, 33] (Becke 3) or the parameters developed for Becke’s Half & Half method [31]. A number of recently developed hybrid and non-hybrid functionals are also included. The zero-damping, two-body only D3 correction of Grimme et al. [50, 51] is available for many of the functionals. Some functionals with the D3 correction are included in the recommended A posteriori corrected functionals list; the rest are in the Other list. These functionals have -D3 appended to the uncorrected functional name. The D3(BJ), D3M and D3M(BJ) corrections are also available.

The available functionals are listed in the tables in The dftname Keyword in the Jaguar Input File, with a description and references. Functionals for which the D3 correction is available are indicated in these tables. The names of the functionals are values of the keyword dftname, which you can use in the gen section of the input file to specify the functional.

The following topics describe the B3LYP-MM and the B3LYP-LOC a posteriori-corrected functionals and constrained DFT calculations.