Auxiliary basis sets

It is possible to specify more than one basis set. For example, by typing

 1:BASIS
 2:4-31G** 6-311++G(3df,3pd)

the basis set 6-311++G(3df,3pd) will be used as an auxiliary basis. When using an auxiliary basis, each atom line must contain a basis-set identifier, which at present may take the values Set=1 (orbital basis) or Set=2 (auxiliary basis). Basis sets with Set=1 must be read first, basis sets with Set=2 thereafter. The above also applies to the ATOMBASIS and INTGRL input modes. Examples are provided by the following input files:

 1:BASIS
 2:cc-pVDZ cc-pCVQZ
 3:Direct MP2-R12/cc-pVDZ calculation on H2O
 4:Auxiliary basis: cc-pCVQZ
 5:Atomtypes=1 Generators=1 X
 6:Charge=8.0 Atoms=1 Set=1
 7:O       .000000000000000    .000000000000000  -0.124309000000000       *
 8:Charge=1.0 Atoms=1 Set=1
 9:H      1.427450200000000    .000000000000000   0.986437000000000       *
10:Charge=8.0 Atoms=1 Set=2
11:O       .000000000000000    .000000000000000  -0.124309000000000       *
12:Charge=1.0 Atoms=1 Set=2
13:H      1.427450200000000    .000000000000000   0.986437000000000       *

 1:ATOMBASIS
 2:Direct MP2-R12/cc-pVDZ calculation on H2O
 3:Auxiliary basis: cc-pCVQZ
 4:Atomtypes=4 Generators=1 X
 5:Charge=8.0 Atoms=1 Set=1 Basis=cc-pVDZ
 6:O       .000000000000000    .000000000000000  -0.124309000000000       *
 7:Charge=1.0 Atoms=1 Set=1 Basis=cc-pVDZ
 8:H      1.427450200000000    .000000000000000   0.986437000000000       *
 9:Charge=8.0 Atoms=1 Set=2 Basis=cc-pCVQZ
10:O       .000000000000000    .000000000000000  -0.124309000000000       *
11:Charge=1.0 Atoms=1 Set=2 Basis=cc-pCVQZ
12:H      1.427450200000000    .000000000000000   0.986437000000000       *

Note that the keyword .AUXBAS must be specified in the **INTEGRALS input section to be able to read the above inputs.