Dear all,

Michael Patzschke wrote:
> there is no easy way to compare ADF calculations with calculations made
> with other programs. This is partly due to the fact, that the total energy
> of the assembly at hand is nowhere calculated. But this is not all, also
> there seems to be no article which describes the quality of the basis sets
> in detail or which would explain, how they were constructed. The manual is
> rather vague too, giving no direct comparison either.
>
> Therefore my question, does anyone of you know any reference to an article
> comparing the STO-basis sets in ADF with other basis-sets and do you know
> any article which describes the construction of those ADF basis-sets.

Some references:

Documentation about basis sets at www.scm.com (including comparison
of quality of different STO basis sets):
http://www.scm.com/Doc/Doc2002/BasissetsSummary.pdf

STO basis sets:
Clementi, E.; Roetti, C. At. Data. Nucl. Data. Tabl. 1974, 14, 177.
McLean, A.D.; Mclean, R.S. At. Data. Nucl. Data. Tabl. 1981, 26, 197.

Construction of basis sets in ADF:
Snijders, J.G.; Vernooijs, P.; Baerends, E.J. At. Data. Nucl. Data. Tabl.
1981, 26, 483.

ZORA basis sets, comparison of quality of different STO basis sets:
van Lenthe, E.; Barends, E.J. J. Comp. Chem. 2003, accepted for publication

Even Tempered basis sets were developed by Del Chong.

Some remarks:
For most ADF basis sets the exponents of the STOs were fitted to numerical
calculated atomic
orbitals (overlap criterion).
The ET (even tempered) basis sets of Chong were fitted to numerically
calculated
total and (orbital) energies.

Abstract ZORA basis sets, comparison of quality of different STO basis sets,
van Lenthe, E.; Barends, E.J. J. Comp. Chem. 2003, accepted for publication:
Seven different types of Slater type basis sets for the elements H (Z=1) up to
E118 (Z=118),
ranging from a double zeta valence quality up to a quadruple zeta valence
quality,
are tested in their performance in neutral atomic and diatomic oxide
calculations.
The exponents of the Slater type functions are optimized for
the use in (scalar relativistic) zeroth order regular approximated (ZORA)
equations.
Atomic tests reveal that on average the absolute basis set error
of 0.03 kcal/mol in the density functional calculation of the
valence spinor energies of the neutral atoms
with the largest all electron basis set of quadruple zeta quality
is lower than the average absolute difference of 0.16 kcal/mol in these valence
spinor energies if one compares the results of
ZORA equation with those of the fully relativistic Dirac equation.
This average absolute basis set error increases to about
1 kcal/mol for the all electron basis sets of triple zeta valence quality,
and to approximately 4 kcal/mol for the all electron basis sets of double zeta
quality.
The molecular tests reveal that on average the calculated atomization energies
of 118 neutral diatomic oxides MO,
where the nuclear charge Z of M ranges from Z = 1-118,
with the all electron basis sets of triple zeta quality
with two polarization functions added are within 1-2 kcal/mol
of the benchmark results with the much larger all electron basis sets,
which are of quadruple zeta valence quality
with four polarization functions added.
The accuracy is reduced to about 4-5 kcal/mol if only one polarization function
is used in the triple zeta basis sets, and further reduced to approximately 20
kcal/mol if
the all electron basis sets of double zeta quality are used.
The inclusion of g type STOs to the large benchmark basis sets
had an effect of less than 1 kcal/mol in
the calculation of the atomization energies of the group 2 and group 14
diatomic oxides.
The basis sets that are optimized for calculations
using the frozen core approximation (frozen core basis sets)
have a restricted basis set in the core region
compared to the all electron basis sets.
On average the use of
these frozen core basis sets give atomic basis set errors which are
approximately
twice as large as the corresponding all electron basis set errors
and molecular atomization energies which are close
to the corresponding all electron results.
Only if spin-orbit coupling is included in the frozen core calculations
larger errors are found, especially for the heavier elements, due to
the additional approximation that is made that the basis functions
are orthogonalized on scalar relativistic core orbitals.

 
Best regards
Erik van Lenthe

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Dr. Erik van Lenthe SCIENTIFIC COMPUTING & MODELLING NV
Tel: +31 20 44 47625 Vrije Universiteit, Theoretische Chemie
secretary: 44 47519 De Boelelaan 1083
 fax: 44 47629 1081 HV Amsterdam, The Netherlands
 e-mail: vanlenthe@scm.com http://www.scm.com
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Received on 2003-02-05 12:10:59