FIG. 33.

Illustration of OpenMP parallel scaling for DFT calculations. The first example is a single-point energy evaluation in a large basis set (M06-2X/def2-QZVPPD, blue diamonds), as might be performed after structure optimization in a smaller basis set. The other two examples are for the evaluation of the DFT energy and gradient in a triple-ζ basis, as often used for geometry optimization. One case is with a semilocal functional (B97M-V/def2-TZVP, orange circles), and the other uses a hybrid functional (ωB97M-V/def2-TZVP, gray squares). All calculations were performed on a 32 core dual-socket Intel Xeon CPU E5-2697A server.