Methods are encoded in the following format:
P– optional capital letter denoting SCF type: 'R' for restricted and 'U' for unrestricted (spin polarized) SCF
METHOD– capitalized name of the method itself (also allowed are digits,+,-)
parameters– parameters (basis set, force field etc), must start with a small letter
Name of the method itself includes core method optionally followed by a suffix separated by '-'. Examples of methods
Basis set encode four parts: family (in lowercase), size (positive integer), variations (suffix), and k-grid (if calculations are not converged with respect to k-sampling).
In case of multiple sets they are separated by "x", e.g. "p2pxa3p" means "p2p" for elements up to Ar and "a3p" for heavier elements.
Basis set family:
Basis set size can denote one of
Possible values of the suffix for pseudopotentials are interpreted as in VASP manual ("s" for softer, "h" for harder, "sv", "pv", "d").
Possible values of the suffix for gaussian basis sets are interpreted as follows. A letter may indicate additional functions: "p" polarization orbitals, "a" diffuse orbitals. Immediately after that letter the description may follow. The description of polarization orbitals follows the Gaussian notations with commas and parentheses omitted, e.g. "3df2pd" means 3d plus 1f orbitals for nonhydrogens and 2 sp-orbitals plus 1 d-orbital on hydrogens. The absence of the description implies a default polarization basis ("p" for smaller one, "pp" for larger one), e.g. "p2p"="p2pd", "p2pp"="p2pdp". The description of diffuse orbitals is currently limited to two cases: absence of the description means a diffusion orbital on nonhydrogens, an additional "a" means a diffusion orbital on all atoms. See also Gaussian manual.
Possible values of k-grid are currently include Gamma-centered grids in the format "Gn1n2n3", where 1<ni<10 denotes number of k-points in i-th directions. Repetitive "ni" or "ni" fixed by symmetry should not be included, e.g. "G5" for isotropic 2D systems means "G551".