Specify the details of the radial quadrature scheme. Four different radial schemes are available, specified by method = EM, BECKE, AHLRICHS or LOG, with the latter being the default.
EM is the Euler-Maclaurin scheme
defined by C. W. Murray, N. C. Handy and G. J. Laming,
Mol. Phys. 78 (1993) 997. , for which the default value is 2,
is defined in equation (6) of the above as
LOG is the scheme described by M. E. Mura and P. J. Knowles,
J. Chem. Phys. 104 (1996) 9848. It is based on the transformation
BECKE is as defined by A. D. Becke, J. Chem. Phys. 88 (1988) 2547.
It is based on the transformation
AHLRICHS is the radial scheme defined by O. Treutler and R. Ahlrichs,
J. Chem. Phys. 102 (1995) 346.
It is based on the transformation their M4 mapping
, , , are the degrees of quadrature (see equation (3) of Murray et al.), for hydrogen/helium, first row, second row, and other elements respectively.
accr as given by the THR command
specifies a target accuracy; the number of radial points is
chosen according to a model, instead of using an explicit .
The stricter of ,
accr is used, unless either
is zero, in which case it is ignored.