$BASIS

$BASIS group (optional)

This group allows certain standard basis sets to be easily given. If this group is omitted, the basis set must be given instead in the $DATA group.

GBASIS
= Name of the Gaussian basis set.

= MINI - Huzinaga's 3 gaussian minimal basis set.
Available H-Rn.

= MIDI - Huzinaga's 21 split valence basis set.
Available H-Xe.

= STO - Pople's STO-NG minimal basis set.
Available H-Xe, for NGAUSS=2,3,4,5,6.

= N21 - Pople's N-21G split valence basis set.
Available H-Xe, for NGAUSS=3.
Available H-Ar, for NGAUSS=6.

= N31 - Pople's N-31G split valence basis set.
Available H-Ne,P-Cl for NGAUSS=4.
Available H-He,C-F for NGAUSS=5.

Available H-Ar, for NGAUSS=6.
For Ga-Kr, N31 selects the BC basis.

= N311 - Pople's "triple split" N-311G basis set.
Available H-Ne, for NGAUSS=6.
Selecting N311 implies MC for Na-Ar.

= DZV - "double zeta valence" basis set.
a synonym for DH for H,Li,Be-Ne,Al-Cl.
a synonym for BC for Ga-Kr.

= DH - Dunning/Hay "double zeta" basis set.
(3s)/[2s] for H.
(9s,4p)/[3s,2p] for Li.
(9s,5p)/[3s,2p] for Be-Ne.
(11s,7p)/[6s,4p] for Al-Cl.

= BC - Binning/Curtiss "double zeta" basis set.
(14s,11p,5d/[6s,4p,1d] for Ga-Kr.

= TZV - "triple zeta valence" basis set.
(5s)/[3s] for H.
(10s,3p)/[4s,3p] for Li.
(10s,6p)/[5s,3p] for Be-Ne.
a synonym for MC for Na-Ar.
(14s,9p)/[8s,4p] for K-Ca.
(14s,11p,6d)/[10s,8p,3d] for Sc-Zn.

= MC - McLean/Chandler "triple split" basis.
(12s,9p)/[6s,5p] for Na-Ar.
Selecting MC implies 6-311G for H-Ne.

additional values for GBASIS are on the next page.

the next two are ECP bases only

GBASIS
= SBK - Stevens/Basch/Krauss/Jasien/Cundari valence basis set, for Li-Rn. This choice implies an unscaled -31G basis for H-He.

= HW - Hay/Wadt valence basis. This is a -21 split, available Na-Xe, except for the transition metals. This implies a 3-21G basis for H-Ne.

semiempirical basis sets

The elements for which these exist can be found in the 'further information' section of this manual. If you pick one of these, all other data in this group is ignored.

GBASIS
= MNDO - selects MNDO model hamiltonian

= AM1 - selects AM1 model hamiltonian

= PM3 - selects PM3 model hamiltonian

NGAUSS
= the number of Gaussians (N). This parameter pertains only to GBASIS=STO, N21, N31, or N311.

NDFUNC
= number of heavy atom polarization functions to be used. These are usually d functions, except for MINI/MIDI. The term "heavy" means Na on up when GBASIS=STO, HW, or N21, and from Li on up otherwise. The value may not exceed 3. The variable POLAR selects the actual exponents to be used, see also SPLIT2 and SPLIT3. (default=0)

NFFUNC
= number of heavy atom f type polarization functions to be used on Li-Cl. This may only be input as 0 or 1. (default=0)

NPFUNC
= number of light atom, p type polarization functions to be used on H-He. This may not exceed 3, see also POLAR. (default=0)

DIFFSP
= flag to add diffuse sp (L) shell to heavy atoms. Heavy means Li-F, Na-Cl, Ga-Br, In-I, Tl-At.
The default is .FALSE.

DIFFS
= flag to add diffuse s shell to hydrogens.
The default is .FALSE.

POLAR
= exponent of polarization functions

= POPLE (default for all other cases)

= POPN311 (default for GBASIS=N311, MC)

= DUNNING (default for GBASIS=DH, DZV)

= HUZINAGA (default for GBASIS=MINI, MIDI)

= HONDO7 (default for GBASIS=TZV)

SPLIT2
= an array of splitting factors used when NDFUNC or NPFUNC is 2. Default=2.0,0.5

SPLIT3
= an array of splitting factors used when NDFUNC or NPFUNC is 3. Default=4.00,1.00,0.25


The splitting factors are from the Pople school, and are probably too far apart. See for example the Binning and Curtiss paper. For example, the SPLIT2 value will usually cause an INCREASE over the 1d energy at the HF level for hydrocarbons.

The actual exponents used for polarization functions, as well as for diffuse sp or s shells, are described in the 'Further References' section of this manual. This section also describes the sp part of the basis set chosen by GBASIS fully, with all references cited.

Note that GAMESS always punches a full $DATA group. Thus, if $BASIS does not quite cover the basis you want, you can obtain this full $DATA group from EXETYP=CHECK, and then change polarization exponents, add Rydbergs, etc.


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