Examples are given in the tables below and follow the standard format generally adopted for specifying basis sets. The single exception applies to additional diffuse functions. These are best inserted in a similar manner to the polarization functions; in parentheses with the light atom designation following heavy atom designation. (i.e., heavy, light). Use a period (.) as a placeholder (see examples).







2,3,6 





3 





4,6 





6 


,, 
,, 
Symbolic Name 
Atoms Supported 
STO2G 
H, He, LiNe, NaAr, K, Ca, Sr 
STO3G 
H, He, LiNe, NaAr, KKr, RbSb 
STO6G 
H, He, LiNe, NaAr, KKr 
321G 
H, He, LiNe, NaAr, KKr, RbXe, Cs 
431G 
H, He, LiNe, PCl 
631G 
H, He, LiNe, NaAr, KZn 
6311G 
H, He, LiNe, NaAr, GaKr 
G3LARGE 
H, He, LiNe, NaAr, KKr 
G3MP2LARGE 
H, He, LiNe, NaAr, GaKr 
Symbolic Name 
Atoms Supported 
321G 
H, He, LiNe, NaAr, KKr, RbXe, Cs 
321+G 
H, He, NaCl, NaAr, K, Ca, GaKr 
321G* 
H, He, NaCl 
631G 
H, He, LiNe, NaAr, KZn, GaKr 
631+G 
H, He, LiNe, NaAr, GaKr 
631G* 
H, He, LiNe, NaAr, KZn, GaKr 
631G(d,p) 
H, He, LiNe, NaAr, KZn, GaKr 
631G(.,+)G 
H, He, LiNe, NaAr, GaKr 
631+G* 
H, He, LiNe, NaAr, GaKr 
6311G 
H, He, LiNe, NaAr, GaKr 
6311+G 
H, He, LiNe, NaAr 
6311G* 
H, He, LiNe, NaAr, GaKr 
6311G(d,p) 
H, He, LiNe, NaAr, GaKr 
G3LARGE 
H, He, LiNe, NaAr, KKr 
G3MP2LARGE 
H, He, LiNe, NaAr, GaKr 
SV, DZ, TZ 


# sets of heavy atom diffuse functions 

# sets of light atom diffuse functions 

# sets of d functions on heavy atoms 

# sets of p functions on light atoms 
Symbolic Name 
Atoms Supported 
SV 
H, LiNe 
DZ 
H, LiNe, AlCl 
TZ 
H, LiNe 
Symbolic Name 
Atoms Supported 
SV 
H, LiNe 
SV* 
H, BNe 
SV(d,p) 
H, BNe 
DZ 
H, LiNe, AlCl 
DZ+ 
H, BNe 
DZ++ 
H, BNe 
DZ* 
H, LiNe 
DZ** 
H, LiNe 
DZ(d,p) 
H, LiNe 
TZ 
H, LiNe 
TZ+ 
H, LiNe 
TZ++ 
H, LiNe 
TZ* 
H, LiNe 
TZ** 
H, LiNe 
TZ(d,p) 
H, LiNe 
Symbolic Name 
Atoms Supported 
ccpVDZ 
H, He, BNe, AlAr, GaKr 
ccpVTZ 
H, He, BNe, AlAr, GaKr 
ccpVQZ 
H, He, BNe, AlAr, GaKr 
ccpCVDZ 
BNe 
ccpCVTZ 
BNe 
ccpCVQZ 
BNe 
augccpVDZ 
H, He, BNe, AlAr, GaKr 
augccpVTZ 
H, He, BNe, AlAr, GaKr 
augccpVQZ 
H, He, BNe, AlAr, GaKr 
augccpCVDZ 
BF 
augccpCVTZ 
BNe 
augccpCVQZ 
BNe 
Symbolic Name 
Atoms Supported 
TZV 
LiKr 
VDZ 
HKr 
VTZ 
HKr 
Symbolic Name 
Atoms Supported 
pc0, pc1, pc2, pc3, pc4 
HAr 
pcJ0, pcJ1, pcJ2, pcJ3, pcJ4 
HAr, except Li, Be, Na, Mg 
pcS0, pcS1, pcS2, pcS3, pcS4 
HAr 
QChem offers a number of standard and special customization features. One of the most important is that of supplying additional diffuse functions. Diffuse functions are often important for studying anions and excited states of molecules, and for the latter several sets of additional diffuse functions may be required. These extra diffuse functions can be generated from the standard diffuse functions by applying a scaling factor to the exponent of the original diffuse function. This yields a geometric series of exponents for the diffuse functions which includes the original standard functions along with more diffuse functions.
When using very large basis sets, especially those that include many diffuse functions, or if the system being studied is very large, linear dependence in the basis set may arise. This results in an overcomplete description of the space spanned by the basis functions, and can cause a loss of uniqueness in the molecular orbital coefficients. Consequently, the SCF may be slow to converge or behave erratically. QChem will automatically check for linear dependence in the basis set, and will project out the neardegeneracies, if they exist. This will result in there being slightly fewer molecular orbitals than there are basis functions. QChem checks for lineardependence by considering the eigenvalues of the overlap matrix. Very small eigenvalues are an indication that the basis set is close to being linearly dependent. The size at which the eigenvalues are considered to be too small is governed by the $rem variable BASIS_LIN_DEP_THRESH. By default this is set to 6, corresponding to a threshold of . This has been found to give reliable results, however, if you have a poorly behaved SCF, and you suspect there maybe linear dependence in you basis, the threshold should be increased.
PRINT_GENERAL_BASIS
Controls print out of built in basis sets in input format
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
TRUE
Print out standard basis set information
FALSE
Do not print out standard basis set information
RECOMMENDATION:
Useful for modification of standard basis sets.
BASIS_LIN_DEP_THRESH
Sets the threshold for determining linear dependence in the basis set
TYPE:
INTEGER
DEFAULT:
6
Corresponding to a threshold of
OPTIONS:
Sets the threshold to
RECOMMENDATION:
Set to 5 or smaller if you have a poorly behaved SCF and you suspect linear dependence in you basis set. Lower values (larger thresholds) may affect the accuracy of the calculation.