Electronic Structures - Chemistry

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6 Mixing of polarization function is small, but gives more flexible wavefunction. 6-311G(3df,2p) adding three d functions and one f functions on non-H atoms and adding two p functions on H atoms. Adding diffuse function 6-311++G first ‘+’ means adding diffuse function on non-H atom. second ‘+’ means adding diffuse function on H atom. Various options for Basis Set specification The following basis sets are stored internally in the Gaussian 98 program. ♦ STO-3G ♦ 3-21G ♦ 6-21G ♦ 4-31G ♦ 6-31G ♦ 6-311G ♦ D95V : Dunning-Huzinaga valence double-zeta ♦ D95 : Dunning-Huzinaga full double zeta ♦ SHC : D95V on first row, Goddard/ Smedley ECP on second row ♦ CEP-4G : Stephens-Basch-Krauss ECP minimal basis ♦ CEP-31G : Stephens-Basch-Krauss ECP split valance ♦ CEP-121G : Stephens-Basch-Krauss ECP triple-split basis ♦ LanL2MB : STO - 3G on first row, Los Alamos ECP plus MBS on Na - Bi ♦ LanL2DZ : D95 on first row, Los Alamos ECP plus DZ on Na-Bi ♦ cc-pVDZ, cc-pVTZ, cc-pVQZ, cc-pV5Z : Dunning’s correlation consistent basis sets (double, triple, quadruple, and quintuple - zeta, respectively). 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: ♦ aug-cc-pVDZ, aug-cc-pVTZ, aug-cc-pVQZ, aug-cc-pV5Z : Dunning’s correlation consistent basis sets, augmented with diffuse functions. Atoms cc-pVDZ cc-pVTZ cc-pVQZ cc-pV5Z H 2s, 1p 3s, 2p, 1d 4s, 3p, 2d, 1f 5s, 4p, 3d, 2f, 1g He 2s, 1p 3s, 2p, 1d 4s, 3p, 2d, 1f not available B - He 3s, 2p, 1d 4s, 3p, 2d, 1f 5s, 4p, 3d, 2f, 1g 6s, 5p, 4d, 3f, 2g, 1h Al - Ar 4s, 3p, 1d 5s, 4p, 2d, 1f 6s, 5p, 3d, 2f, 1g 7s, 6p, 4d, 3f, 2g, 1h 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) Adding Polarization and Diffuse Functions Single first polarization functions can also be requested using the usual * or ** notation. Note that (d,p) and ** are synonymous – 6-31G** is equivalent to 6-31G(d,p), for example – and that the 3-21G * basis set has polarization functions on second row atoms only. The + and ++
7 diffuse functions are available with some basis sets, as are multiple polarization functions. The keyword syntax is best illustrated by example: 6-31+G(3df,2p) designates the 6-31G basis set supplemented by diffuse functions, 3 sets of d functions and one set of f functions on heavy atoms, and supplemented by 2 sets of p functions on hydrogens. When the AUG- prefix is used to add diffuse function to the cc-pVxZ basis sets, one diffuse function of each function type in use for a given atom is added. For example, the augcc-pVTZ basis places one s, one d, and one p diffuse functions on hydrogen atoms, and one d, one p, one d, and one f diffuse functions on B through Ne and AI through Ar. Adding a single polarization function to 6-31G (i.e. 6-311G(d)) will result in one d function for first and second row atoms and one function for first transition row atoms, since d functions are already present for the valence electrons latter. Similarly, adding a diffuse function to the 6- 311G basis set will produce one s, one p, and one d diffuse functions for third - row atoms. The following table lists polarization and diffuse function availability and the range of applicability for each built-in basis set in Gaussian 94: Polarization Diffuse Basis set Available atoms Functions Functions STO-3G H - Xe (d) 3-21G H - Xe (d) or (d, p) + 6-21G H - Cl (d) 4-31G H - Ne (d) or (d, p) 6-31G H - Cl (3df, 3pd) ++ 6-311G H - Br (3df, 3pd) ++ D95 H - Cl (3df, 3pd) ++ D95V H - Cl (d) or (d, p) ++ SHC H - Cl (3df, 3pd) ++ CEP-4G H - Cl (3df, 3pd) ++ CEP-31G H - Cl (3df, 3pd) ++ CEP-121G H - Cl (3df, 3pd) ++ LanL2MB H - Ba, La - Bi LanL2DZ H, Li - Ba, La - Bi cc-pVxZ H - He, B - Ne, Al - Ar included in added via
Page 1 and 2: Our task: To learn how to do ab ini
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Page 11 and 12: 11 Largest concise Abelian subgroup

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