If a basis is not specified at all for any unique atom group, then the
program assumes a global default.
Presently, this default is `VDZ`, but may be overridden using

`BASIS`,*basis*

or

`BASIS=`*basis*

*basis* is looked up in the file `lib/defbas`, which generates
an appropriate
request for a complete contracted set, together in some cases with an
ECP, from the
library.
This mapping includes the following commonly-used basis sets:

- All of the Dunning correlation consistent basis sets, through the use of
either the standard name of the basis set (
`cc-pVXZ`,`aug-cc-pVXZ`) or an abbreviation (`VXZ`,`AVXZ`). For Al-Ar the tight-d augmented sets are obtained through the standard name`cc-pV(X+d)Z`,`aug-cc-pV(X+d)Z`or`VXZ+d`,`AVXZ+d`. Sets X=D,T,Q,5 are available for H-Kr with X=6 available for B-Ne and Al-Ar. - The correlation consistent basis sets for core correlation,
`cc-pCVXZ`,`aug-cc-pCVXZ`or`CVXZ`,`ACVXZ`(X=D,T,Q,5), and the newer ”weighted sets”`cc-pwCVXZ`,`aug-cc-pwCVXZ`or`WCVXZ`,`AWCVXZ`(X=D,T,Q,5). These are available for Li-Kr (CVXZ do not include Sc-Zn). - Douglas-Kroll-Hess relativistic versions of the correlation consistent basis sets are available through
use of the standard or abbreviated names with extension -DK, e.g.,
`cc-pVXZ-DK`or`VXZ-DK`. X=D-5 are available for H-Kr, while X=T are available for Y-Cd and Hf-Hg. Sets contracted for 3rd-order DKH are available for Hf-Hg with extension -DK3. - The F12 basis sets of Peterson et al. for explicitly correlated calculations,
`cc-pVXZ-F12`,`cc-pCVXZ-F12`or`VXZ-F12`,`CVXZ-F12`with X=D,T,Q. These are available for H-Ar. - The Turbomole def2 family of basis sets,
`SV(P)`,`SVP`,`TZVP`,`TZVPP`,`QZVP`, and`QZVPP`. These are available for the entire periodic table except for the f-block elements. - The older segmented Dunning/Hay double-zeta sets for the first row (
`DZ`and`DZP`). - The Roos ANO basis sets for H-Ar (
`ROOS`). - The Stuttgart ECPs and associated basis sets (e.g.,
`ECP10MDF`), as well as the ECP-based correlation consistent basis sets of Peterson and co-workers,`cc-pVXZ-PP`,`aug-cc-pVXZ-PP`,`cc-pwCVXZ-PP`,`aug-cc-pwCVXZ-PP`or`VXZ-PP`,`AVXZ-PP`,`WCVXZ-PP`,`AWCVXZ-PP`. The latter are available for Cu-Kr, Y-Xe, and Hf-Rn (core correlation sets currently only for transition metals). - The Hay ECPs and corresponding basis sets (
`ECP1`and`ECP2`). - Other members of the Karslruhe basis sets (
`SV`,`TZV`, and, for some elements,`TZVPPP`). - The Binning/Curtiss sets for Ga-Kr (
`BINNING-SV`,`BINNING-SVP`,`BINNING-VTZ`and`BINNING-VTZP`) - Most of the Pople basis sets, using their standard names (e.g.,
`6-31G*, 6-311++G(D,P)`, etc.). Note that specially in this case, the mechanism described below using parenthesized modifiers to restrict the basis set is disabled to allow the full range of standard basis sets to be specified.

In addition, many density fitting and resolution of the identity (RI) basis sets are available. For the correlation consistent basis sets of Dunning, the appropriate VXZ/JKFIT, VXZ/MP2FIT, AVXZ/MP2FIT sets of Weigend are chosen automatically in density fitted calculations (augmented versions AVXZ/JKFIT for Fock-matrix fitting are also available, but not used by default). For the def2 family of orbital basis sets, the appropriate auxiliary sets (e.g., TZVPP/JFIT, TZVPP/JKFIT, TZVPP/MP2FIT) are used. In principle these JKFIT sets are universal and also applicable in combination with the AVXZ basis sets. Initial results indicate that they also work well with the cc-pVXZ-PP and aug-cc-pVXZ-PP series of basis sets.

For explicitly correlated F12 calculations that use the cc-pVXZ-F12 orbital basis sets, the corresponding VXZ-F12/OPTRI basis sets are used by default to construct the complementary auxiliary orbital basis (CABS). For other orbital basis sets, appropriate JKFIT sets are utilized by default.

Example:

`BASIS=VTZ`

generates valence triple zeta basis set for all atoms. Thus, the input

performs a Hartree-Fock calculation for HO using the cc-pVTZ basis set.

Default basis sets can be defined anywhere in the input before the energy calculation
to which it should apply using a single `BASIS` card as shown above. The default basis set
applies to all types of atoms but can be superceded by different basis sets
for specific atoms as explained in the next section. Some restrictions concerning the
maximum angular momentum functions to be used, or the number of contracted functions
are possible as follows:

The maximum angular momentum in the basis set can be reduced using syntax such as

`BASIS,VQZ(D)`

which would omit the and functions that would normally be present in the VQZ basis set.

`BASIS,VQZ(D/P)`

would specify additionally a maximum angular momentum of on hydrogen, i.e. would omit orbitals on hydrogen.

For generally contracted basis sets, an extended syntax can be used to explicitly give the number of contracted functions of each angular momentum. For example,

`BASIS,ROOS(3s2p1d/2s)`

generates a `6-31G*`-sized basis set from the Roos ANO
compilation.

Notes: *basis* must not be variable called BASIS. Furthermore, input like

`$BASIS=[AVDZ, AVTZ, AVQZ]`

is not allowed, i.e. the keyword `BASIS` must not be preceded with $.
One can loop over several basis sets using, for example, using

$aobases=[AVDZ, AVTZ, AVQZ] do ibas=1,#aobases basis=aobases(ibas) ... enddo

molpro@molpro.net 2019-01-22