MOLPRO

11 BASIS INPUT 75
If an individual basis function type (s, p, d, etc.) is specified for an atom, it is required that all
other types are also defined, i.e., as soon as an explicit definition of a basis function for an atom
is given, all defaults are erased for this atom.
There are four different input forms for basis functions, as explained below under a) to d). In
case that options (e.g. SCALE, NPRIM) are specified, they can be given in any order, but no
value without option key must be given after an option.
In all four cases type defines the angular symmetry (S, P, D, F, G, H, or I). type can
include several types, e.g., SPD or DF (this usually makes sense only with or default library
contractions or no contractions). The basis is loaded for all atoms with tag name atom in the
geometry input. If atom is an integer, it refers to a z-matrix row.
a) Library basis sets:
type,atom,name,scale2,nprim;
or
type,atom,name,[SCALE=scale|SCALE2=scale2],[NPRIM=nprim|DELETE=ndel];
Load basis named name from the library
If scale or scale2 is present, all exponents are scaled by scale or scale**2, respectively. If nprim
is specified, the first nprim exponents only are taken from the library. If nprim is negative or
ndel is given, the last |nprim| (ndel) basis functions from the library set are deleted. Associated
with the library basis may be a set of default contraction coefficients which may be accessed
in subsequent contraction cards. type can include several types, e.g., SPD or DF. This usually
makes sense only with default contractions, i.e., such cards should be followed only by “C”
without any other specifications for contractions.
b) Explicit basis input:
type,atom,exp1,exp2,...expn;expn+1,...;
General specification of exponents; continuation onto subsequent cards (separated by semicolon)
is permitted as shown (the first card can hold up to 19 exponents, each following card 20
exponents.
The exponents (and other numerical parameters described below such as numbers of functions,
and contraction coefficients) can be given as general input expressions, possibly involving variables.
It is important to note, however, that these expressions are evaluated typically just once,
at the same time as the complete basis set is parsed. This generally happens the first time that
the basis set is required, perhaps before the first SCF calculation can be done. If the variables on
which the basis depends are altered, this will not be noticed by the program, and the new basis
set will not be used for subsequent stages of the computation. If, however, a new basis block is
presented in the input, then the program marks as outdated any quantities such as integrals that
have been calculated with the old basis set; subsequent job steps will then use the new basis.
c) Even tempered basis sets:
type,atom,EVEN,nprim,ratio,centre,dratio
or
type,atom,EVEN,NPRIM=nprim,[RATIO=ratio],[CENTRE=centre],[DRATIO=dratio]
Generates a generalized even tempered set of functions. The number of functions n is specified
by nprim, their geometric mean c by centre, the mean ratio of successive exponents r by ratio,
and the variation of this ratio, d, by dratio. If centre is not given, the previous basis of the same
type is extended by diffuse functions. If in this case ratio is not given, r is determined from