Gaussian-3 (G3) Theory

First- and second-row

Third-row nontransition s

References

G3 THEORY FOR THE FIRST AND SECOND-ROW

Gaussian-3 theory1 is the third in a series of Gx methods for calculation of molecular energies. It is a composite technique in which a sequence of well-defined ab initio molecular orbital calculations is performed to arrive at a total energy of a given molecular species. Geometries are determined using second-order Moller-Plesset perturbation theory. Correlation level calculations are done using Moller-Plesset perturbation theory up to fourth-order and with quadratic configuration interaction. Large basis sets, including multiple sets of polarization functions, are used in the correlation calculations. One of these basis sets is the G3Large basis set given below. A series of additivity approximations makes the technique fairly widely applicable.

A new test set, referred to as the G2/97,2,3 has been used to assess G3 theory. It includes 148 enthalpies of formation, 88 ionization potentials, 58 electron affinities, and 8 proton affinities. The comprehensive set, which includes the original G2 test set, contains 302 entries. Data for this test set are given in the web page.

A modification of G3 theory that uses reduced orders of Moller-Plesset perturbation theory is G3(MP2) theory.4 This method saves considerable computational time compared to G3 theory with some loss in accuracy, but is much more accurate that G2(MP2) theory. The G3MP2Large basis set, given below, is used in G3(MP2) theory. Another modification that uses reduced orders of Moller-Plesset perturbation theory is G3(MP3) theory.5 This method is based on third-order perturbation theory (MP3) and uses the G3Large basis set.

G3 THEORY FOR THE THIRD-ROW NONTRANSITION

G3 theory has been extended to molecules containing third-row non-transition metal elements K, Ca, Ga-Kr.7 The G3 total energies, components of the energies, higher level corrections, and zero-point energies are given in the link below. Also given are basis sets and geometries.

REFERENCES

1. "Gaussian-3 theory for molecular energies of first- and second-row compound" L.A. Curtiss, K. Raghavachari, P.C. Redfern, V.Rassolov, and J. A. Pople, Journal of Chemical Physics, 109, 7764 (1998).

2. "Assessment of Gaussian-2 and Density Functional Methods for the Computation of Enthalpies of Formation" L. A. Curtiss, K. Raghavachari, P. C. Redfern, and J. A. Pople, Journal of Chemical Physics 106, 1063 (1997).

3. "Assessment of Gaussian-2 and Density Functional Methods for the Computation of Ionization Energies and Electron Affinities" L. A. Curtiss, P. C. Redfern, K. Raghavachari, and J. A. Pople, Journal of Chemical Physics 109, 42 (1998).

4. "Gaussian-3 Theory Using Reduced Moller-Plesset Orders," L. A. Curtiss, P. C. Redfern, K. Raghavachari, V. Rassolov, and J. A. Pople, Journal of Chemical Physics, 110, 4703 (1999).

5. Gaussian-3 Theory: A Variation Based on Third-Order Perturbation Theory and an Assessment the Contribution of Core-Related Correlation, L. A. Curtiss, P. C. Redfern, K. Raghavachari, and J. A. Pople, Chemical Physics Letters, 313, 600-607 (1999).

6. "The Relativistic Dirac-Coulomb-Fock Effect on Atomizatiom Energies," G. S. Kedziora, J. A. Pople, V. A. Rassolov, M. Ratner, P. C. Redfern, and L. A. Curtiss, Journal of Chemical Physics, 110, 7123-7126 (1999).

7. Extension of Gaussian-3 theory to moelcules containing third-row atoms K, Ca, Ga-Kr L. A. Curtiss, P. C. Redfern, V. Rassolov, G. Kedziora, J. A. Pople, Journal of Chemical Physics, in press.

 Bibliography of Gaussian-n papers

For more information contact Larry Curtiss e-mail: curtiss@anl.gov