Gaussian 03 Online ManualLast update: 7 March 2008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||

Most methods require a basis set be specified; if no basis set keyword is included in the route section, then the STO-3G basis will be used. The exceptions consist of a few methods for which the basis set is defined as an integral part of the method; they are listed below: All semi-empirical methods, including **ZINDO**for excited states.All molecular mechanics methods. Compound model chemistries: all G *n*, CBS and W1 methods.
The following basis sets are stored internally
in the -
6-31G†: *Gaussian 03*also includes the 6-31G† and 6-31G†† basis sets of George Petersson and coworkers, defined as part of the Complete Basis Set methods [88,327]. These are accessed via the**6-31G**(**d'**) and**6-31G**(**d',p'**) keywords, to which single or double diffuse functions may also be added; f functions may also be added: e.g.,**6-31G(d'f)**, and so on. **6-311G**: Specifies the 6-311G basis for first-row atoms and the McLean-Chandler (12s,9p) (621111,52111) basis sets for second-row atoms [328,329] (note that the basis sets for P, S, and Cl are those called "negative ion" basis sets by McLean and Chandler; these were deemed to give better results for neutral molecules as well), the basis set of Blaudeau and coworkers for Ca and K [322], the Wachters-Hay [330,331] all electron basis set for the first transition row, using the scaling factors of Raghavachari and Trucks [332], and the 6-311G basis set of McGrath, Curtiss and coworkers for the other elements in the third row [324,333,334]. Note that Raghavachari and Trucks recommend both scaling and including diffuse functions when using the Wachters-Hay basis set for first transition row elements; the**6-311+G**form must be specified to include the diffuse functions.**MC-311G**is a synonym for**6-311G**.**D95V**: Dunning/Huzinaga valence double-zeta [335].**D95**: Dunning/Huzinaga full double zeta [335].**SHC**: D95V on first row, Goddard/Smedley ECP on second row [335,336]. Also known as**SEC**.**CEP-4G**: Stevens/Basch/Krauss ECP minimal basis [337,338,339].**CEP-31G**: Stevens/Basch/Krauss ECP split valance [337,338,339].**CEP-121G**: Stevens/Basch/Krauss ECP triple-split basis [337,338,339].*Note that there is only one CEP basis set defined beyond the second row, and all three keywords**are equivalent for these atoms.*-
**LanL2MB**: STO-3G [309,310] on first row, Los Alamos ECP plus MBS on Na-La, Hf-Bi [340,341,342]. -
**LanL2DZ**: D95V on first row [335], Los Alamos ECP plus DZ on Na-La, Hf-Bi [340,341,342]. **SDD**: D95V up to Ar [335] and Stuttgart/Dresden ECPs on the remainder of the periodic table [343,344,345,346,347,348,349,350,351,352,353,354,355,356,357,358,359,360,361,362,363,364,365,366,367]. The**SDD**,**SHF**,**SDF**,**MHF**,**MDF**,**MWB**forms may be used to specify these basis sets/potentials within**Gen**basis input. Note that the number of core electrons must be specified following the form (e.g., MDF28 for the MDF potential replacing 28 core electrons).**SDDAll**: Selects Stuttgart potentials for Z > 2.**cc-pVDZ**,**cc-pVTZ**,**cc-pVQZ**,**cc-pV5Z**,**cc-pV6Z**: Dunning's correlation consistent basis sets [368,369,370,371,372] (double, triple, quadruple, quintuple-zeta and sextuple-zeta, respectively). These basis sets have had redundant functions removed and have been rotated [373] in order to increase computational efficiency.These basis sets include polarization functions by definition. The following table lists the valence polarization functions present for the various atoms included in these basis sets:
These basis sets may be augmented with diffuse functions by adding the **AUG**- prefix to the basis set keyword (rather than using the + and ++ notation-see below). However, the elements He, Mg, Li, Be, and Na do not have diffuse functions defined within these basis sets.MIDI! of Truhlar and coworkers [376]. The **MidiX**keyword is used to request this basis set.**EPR-II**and**EPR-III**: The basis sets of Barone [377] which are optimized for the computation of hyperfine coupling constants by DFT methods (particularly B3LYP). EPR-II is a double zeta basis set with a single set of polarization functions and an enhanced s part: (6,1)/[4,1] for H and (10,5,1)/[6,2,1] for B to F. EPR-III is a triple-zeta basis set including diffuse functions, double d-polarizations and a single set of f-polarization functions. Also in this case the s-part is improved to better describe the nuclear region: (6,2)/[4,2] for H and (11,7,2,1)/[7,4,2,1] for B to F.**UGBS**,**UGBS1P**,**UGBS2P**and**UGBS3P**: The universal Gaussian basis set of de Castro, Jorge and coworkers [378,379,380,381,382,383,384,385,386]. The latter three keyword forms have an additional 1, 2 or three polarization functions for each function in the normal**UGBS**basis set (i.e.,**UGBS1P**adds a p function for each s, a d function for each p and so on;**UGBS2P**adds a p and d function for each s, a d and f function for each p, and**UGBS3P**adds a p, d and f for each s, etc.).**MTSmall**of Martin and de Oliveira, defined as part of their W1 method (see the**W1U**keyword) [94].The **DGDZVP, DGDZVP2**and**DGTZVP**basis sets used in*DGauss*[387,388].
## Adding Polarization and Diffuse FunctionsSingle first polarization functions
can also be requested using the usual When the Adding a single polarization function
to When a frozen-core
calculation is done using the The following table lists polarization
and diffuse function availability and the range of applicability for each built-in
basis set in
## Additional Basis Set-Related KeywordsThe following additional keywords are useful in conjunction with these basis set keywords: **5D**and**6D**: Use 5 or 6 d functions (pure vs. Cartesian d functions), respectively.**7F**and**10F**: Use 7 or 10 f functions (pure vs. Cartesian f functions), respectively. These keywords also apply to all higher functions (g and beyond).
Other
basis sets may also be input to the program using the ## Issues Arising from Pure vs. Cartesian Basis Functions
All of the built-in basis sets use pure f functions. Most also use pure d functions; the exceptions are 3-21G, 6-21G, 4-31G, 6-31G, 6-31G†, 6-31G††, CEP-31G, D95 and D95V. The preceding keywords may be used to override the default pure/Cartesian setting. Note that basis functions are generally converted to the other type automatically when necessary, for example, when a wavefunction is read from the checkpoint file for use in a calculation using a basis consisting of the other type [391]. Within a job, all d functions must be 5D or 6D, and all f and higher functions must be pure or Cartesian. When using the **ExtraBasis**,**Gen**and**GenECP**keywords, the basis set explicitly specified in the route section always determines the default form of the basis functions (for**Gen**, these are**5D**and**7F**). For example, if you use a general basis set taking some functions from the 3-21G and 6-31G basis sets, pure functions will be used unless you explicitly specify**6D**in the route section in addition to**Gen**. Similarly, if you add basis functions for a transition metal from the 6-311G(d) basis set via**ExtraBasis**to a job that specifies the 6-31G(d) basis set in the route section, Cartesian d functions will be used. Likewise, if you want to add basis functions for Xe from the 3-21G basis set to the 6-311 basis set via the**ExtraBasis**keyword, the Xe basis functions will be pure functions.
## Density Fitting Basis SetsGaussian 03 provides the density fitting approximation for pure
DFT calculations [35,36,392].
This approach expands the density in a set of atom-centered functions when computing
the Coulomb interaction instead of computing all of the two-electron integrals.
It provides significant performance gains for pure DFT calculations on medium
sized systems too small to take advantage of the linear scaling algorithms without
a significant degradation in the accuracy of predicted structures, relative energies
and molecular properties. The desired fitting basis set is specified as a third component of the model chemistry, as in this example: # BLYP/6-31G(d)/Auto Note that the slashes are required when a density fitting basis set is specified. The In addition, density fitting sets
can be generated automatically from the AO primitives using By default, no fitting set
is used. Density fitting basis sets may be augmented with the Click here to go on to the next section. |