Gaussian 03 Capabilities
Gaussian has been designed with the needs of the user in
mind. All of the standard input is freeformat and mnemonic.
Reasonable defaults for input data have been provided, and the output
is intended to be selfexplanatory. Mechanisms are available for the
sophisticated user to override defaults or interface their own code to
the Gaussian system. The authors hope that their efforts will
allow users to concentrate their energies on the application of the
methods to chemical problems and to the development of new methods,
rather than on the mechanics of performing the calculations.
The technical capabilities of the Gaussian 03 system
are listed in the subsections below.
Fundamental Algorithms
 Calculation of one and twoelectron integrals over any general
contracted gaussian functions. The basis functions can either be
cartesian gaussians or pure angular momentum functions, and a
variety of basis sets are stored in the program and can be requested
by name. Integrals may be stored in memory, stored externally, or be
recomputed as needed [20,21,22,23,24,25,26,27,28].
The cost of computations can be linearized using fast multipole
method (FMM) and sparse matrix techniques for certain kinds of
calculations [29,30,31,32,33,34].
 Transformation of the atomic orbital (AO) integrals to the
molecular orbital basis by "incore" means (storing the AO integrals
in memory), "direct" means (no integral storage required),
"semidirect" means (using some disk storage of integrals), or
"conventional" means (with all AO integrals on disk).
 Use of density fitting to speed up the Coulomb part of pure DFT
calculations [35,36].
 Numerical quadrature to compute DFT XC energies and their
derivatives.
Energies
 Molecular mechanics calculations using the AMBER [37],
DREIDING [38]
and UFF [39,40]
force fields.
 Semiempirical calculations using the CNDO [41],
INDO [42],
MINDO/3 [43,44],
MNDO [43,45,46,47,48,49,50,51,52],
AM1 [43,48,49,53,54],
and PM3 [55,56]
model Hamiltonians.
 Selfconsistent field calculations using closedshell (RHF) [57],
unrestricted openshell (UHF) [58],
and restricted openshell (ROHF) [59]
HartreeFock wavefunctions.
 Correlation energy calculations using MøllerPlesset
perturbation theory [60]
carried to second, third [61],
fourth [62,63],
or fifth[64]
order. MP2 calculations use direct [21,65]
and semidirect methods [23]
to use efficiently however much (or little) memory and disk are
available.
 Correlation energy calculations using configuration interaction
(CI), using either all double excitations (CID) or all single and
double excitations (CISD) [66].
 Coupled cluster theory with double substitutions (CCD)[67],
coupled cluster theory with both single and double substitutions (CCSD)
[68,69,70,71],
Quadratic Configuration Interaction using single and double
substitutions (QCISD) [72],
and Brueckner Doubles Theory (BD) [73,74].
A noniterative triples contribution may also be computed (as well
as quadruples for QCISD and BD).
 Density functional theory [75,76,77,78,79],
including general, userconfigurable hybrid methods of HartreeFock
and DFT. See this
page for a complete list of available functionals.
 Automated, high accuracy energy methods: G1 theory [80,81],
G2 theory [82],
G2(MP2) [83]
theory, G3 theory [84],
G3(MP2) [85],
and other variants [86];
Complete Basis Set (CBS) [87,88,89,90,91]
methods: CBS4 [91,92],
CBSq [91],
CBSQ [91],
CBSQ//B3 [92,93],
and CBSQCI/APNO [90],
as well as general CBS extrapolation; the W1 method of Martin (with
slight modifications) [94,95,96].
 General MCSCF, including complete active space SCF (CASSCF) [97,98,99,100],
and allowing for the optional inclusion of MP2 correlation [101].
Algorithmic improvements [102]
allow up to 14 active orbitals in Gaussian 03. The
RASSCF variation is also supported [103,104].
 The Generalized Valence BondPerfect Pairing (GVBPP) SCF method
[105].
 Testing the SCF wavefunctions for stability under release of
constraints, for both HartreeFock and DFT methods [106,107].
 Excited state energies using the singleexcitation Configuration
Interaction (CISingles) method [108],
the timedependent method for HF and DFT [109,110,111],
the ZINDO semiempirical method [112,113,114,115,116,117,118,119,120],
and the Symmetry Adapted Cluster/Configuration Interaction (SACCI)
method of Nakatsuji and coworkers [121,122,123,124,125,126,127,128,129,130,131,132,133,134,135].
Gradients and Geometry Optimizations
 Analytic computation of the nuclear coordinate gradient of the
RHF [136],
UHF, ROHF, GVBPP, CASSCF [137,138],
MP2 [22,23,139,140],
MP3, MP4(SDQ) [141,142],
CID [143],
CISD, CCD, CCSD, QCISD, Density Functional, and excited state CIS
energies [108].
All of the postSCF methods can take advantage of the frozencore
approximation.
 Automated geometry optimization to either minima or saddle
points [136,144,145,146,147,148],
using internal or cartesian coordinates or a mixture of coordinates.
Optimizations are performed by default using redundant internal
coordinates [149],
regardless of the input coordinate system used.
 Automated transition state searching using synchronous
transitguided quasiNewton methods [150].
 Reaction path following using the intrinsic reaction coordinate
(IRC) [151,152].
 Two or threelayer ONIOM [153,154,155,156,157,158,159,160,161,162,163]
calculations for energies and geometry optimizations.
 Simultaneous optimization of a transition state and a reaction
path [164].
 Conical intersection optimization using stateaveraged CASSCF [165,166,167].
 IRCMax calculation which locates the point of maximum energy for
a transition structure along a specified reaction path [168,169,170,171,172,173,174,175,176].
 Classical trajectory calculation in which the classical
equations of motion are integrated using analytical second
derivatives [177,178,179,180]
using either:
 Born Oppenheimer molecular dynamics (BOMD) [177,178,179,180,181,182]
(see [183]
for a review) [184,185,186,187,188].
This can be done using any method for which analytic gradients are
available, and can optionally make use of Hessian information.
 Propagation of the electronic degrees of freedom via the Atom
Centered Density Matrix Propagation molecular dynamics model [188,189,190].
This method has similarity and differences to the related CarParrinello
approach [191].
See the discussion of the
ADMP
keyword for details. This can be done using the AM1, HF, and DFT
methods.
Frequencies and Second Derivatives
 Analytic computation of force constants (nuclear coordinate
second derivatives), polarizabilities, hyperpolarizabilities, and
dipole derivatives analytically for the RHF, UHF, DFT, RMP2, UMP2,
and CASSCF methods [25,139,192,193,194,195,196,197,198,199],
and for excited states using CIS.
 Numerical differentiation of energies or gradients to produce
force constants, polarizabilities, and dipole derivatives for the
MP3, MP4(SDQ), CID, CISD, CCD, and QCISD methods [143,200,201,202].
 Harmonic vibrational analysis and thermochemistry analysis using
arbitrary isotopes, temperature, and pressure.
 Analysis of normal modes in internal coordinates.
 Determination of IR and Raman intensities for vibrational
transitions [193,194,196,200,203].
Preresonance Raman intensities are also available.
 Harmonic vibrationrotation coupling [204,205,206,207].
 Anharmonic vibration and vibrationrotation coupling [204,206,207,208,209,210,211,212,213,214].
Anharmonic vibrations are available for the methods for which
analytic second derivatives are available.
Molecular Properties
 Evaluation of various oneelectron properties using the SCF, DFT,
MP2, CI, CCD and QCISD methods, including Mulliken population
analysis [215],
multipole moments, natural population analysis, electrostatic
potentials, and electrostatic potentialderived charges using the
MerzKollmanSingh [216,217],
CHelp [218],
or CHelpG [219]
schemes.
 Static and frequencydependent polarizabilities and
hyperpolarizabilities for HartreeFock and DFT methods [220,221,222,223,224,225].
 NMR shielding tensors and molecular susceptibilities using the
SCF, DFT and MP2 methods [226,227,228,229,230,231,232,233,234,235].
Susceptibilities can now be computed using GIAOs [236,237].
Spinspin coupling constants can also be computed [238,239,240,241]
at the HartreeFock and DFT levels.
 Vibrational circular dichroism (VCD) intensities [242].
 Propagator methods for electron affinities and ionization
potentials [243,244,245,246,247,248,249].
 Approximate spin orbit coupling between two spin states can be
computed during CASSCF calculations [250,251,252,253,254].
 Electronic circular dichroism [255,256,257,258,259]
(see [260]
for a review).
 Optical rotations and optical rotary dispersion via GIAOs [261,262,263,264,265,266,267,268,269,270,271].
 Hyperfine spectra: g tensors, nuclear electric quadrupole
constants, rotational constants, quartic centrifugal distortion
terms, electronic spin rotation terms, nuclear spin rotation terms,
dipolar hyperfine terms, and Fermi contact terms [272,273,274,275,276,277,278,279].
Input can be prepared for the widely used program of H. M. Pickett [280].
Solvation Models
All of these models employ a selfconsistent reaction field (SCRF)
methodology for modeling systems in solution.
 Onsager model (dipole and sphere) [281,282,283,284],
including analytic first and second derivatives at the HF and DFT
levels, and singlepoint energies at the MP2, MP3, MP4(SDQ), CI, CCD,
and QCISD levels.
 Polarized Continuum (overlapping spheres) model (PCM) of Tomasi
and coworkers [285,286,287,288,289,290,291,292,293,294,295,296,297,298,299,300,301,302,303]
for analytic HF, DFT, MP2, MP3, MP4(SDQ), QCISD, CCD, CCSD, CID, and
CISD energies and HF and DFT gradients and frequencies.
 Solvent effects can be computed for excited states [298,299,300].
 Many properties can be computed in the presence of a solvent [304,305,306].
 IPCM (static isodensity surface) model [307]
for energies at the HF and DFT levels.
 SCIPCM (selfconsistent isodensity surface) model [307]
for analytic energies and gradients and numerical frequencies at
the HF and DFT levels.
