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Averaged Atomic Natural Pseudo-Orbital (ANPO) Basis
Sets
A.Zaitsevskii
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| ANPO are the counterparts
of well-known Averaged Atomic Natural Orbitals (ANO) for core pseudopotential
calculations. Its use appears to be recommendable for high-level correlation
and possibly spin-orbit treatment when the computational cost
of integral evaluation stage is negligible while the reduction of basis
set size is of crucial importance for other stages. The employed procedure
of ANPO basis construction is essentially that used to produce density-averaged
ANO in [K.Pierloot, B.Dumez, P.-O.Wildmark, B.O.Roos, Theor.Chim.Acta
90,
87 (1995)]: |
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Normally I started with an even-tempered primitive Gaussian manifold crudely
optimized at SCF (for low momentum values) or AQCC (higher angular momentum
values) levels and extended by one diffuse function per angular momentum.
Innermost d exponents (for atoms with d shell treated explicitely)
were optimized separately . For second row atoms I took f exponents
from [P.-O.Wildmark, B.J.Persson, B.O.Roos, Theor.Chim.Acta
79,
419 (1991)]
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(MC)SCF procedure with averaging over the neutral atom (A), negative ion
(A-) and positive ion (A+) ground states weighted
as 2:1:1 (1:0:1 for rare gas atoms having no negative ions) is employed
to generate initial common orthogonal orbital basis,
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using this common basis, AQCC calculations for A, A-
and
A+ ground states are performed. The resulting densities are
averaged with the same weights 2(A) : 1(A-) : 1(A+)
(or 1(A) : 1(A+) for rare-gas atoms) and then diagonalized
to yield the ANPO.
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the procedure applied to transition elements was somewhat more complicated,
involving electronic states with different d-shell occupancies in
the averaging procedure.
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| The present calculations
were performed by means of (slightly modified) routines from the Columbus
program suite. The ANPO are adapted to the use of shape-consistent core
pseudopotentials of Christiansen et al. (see e.g. [L.A.LaJohn et al., J.Chem.Phys.
87,
2812 (1987)]). For heavier elements, small-core (spd-valence)
pseudopotentials were chosen; to obtain ANPO well suited for sp-only
correlation calculations, the d shell was frozen at AQCC step. Au
basis for use with energy-adjusted small-core pseudopotential [Andrae et
al., Theor.Chim.Acta 77, 123 (1990)] is given. |
Available Basis Sets
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The basis sets are given in the Columbus
format:
line: [comment line]
line: [number_of_contractions]
do i = 1 , [number_of_contractions]
line: [number_of_primitives] [angular_momentum+1] [max_number_of_ANPO]
do j = 1, [number_of_primitives]
line: [exp_of_primitive] ([coef_of_primitive_in_kth_ANPO],
k=1,max_number_of_ANPO])
end do
end do |
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