[molpro-user] Extrapolation to the complete basis set limit of def2-anzvp basis sets.

Peterson, Kirk kipeters at wsu.edu
Wed Oct 23 16:25:38 BST 2013


Dear Alexander (Sasha),

the def2- basis sets to my knowledge were never designed explicitly for basis set extrapolation.  They do provide a series of basis sets that range from small to large, but I am not aware of a study that uses them in CBS extrapolations. You might though want to consider the TZVPP and QZVPP sets since these have f and g functions, respectively, compared to TZVP and QZVP. In any event if you are using lmax-style extrapolations, you only need 2 basis sets to do this. Typically 3-point extrapolations that include a DZ-quality set is not recommended except for specialized extrapolation formulas.

best,

-Kirk

PS - also, you might want to take a look at the top of the file def2-nzvpp-orb.libmol in your molpro lib directory for some notes about def2- vs. dhf-


On Oct 23, 2013, at 5:17 AM, sasha medvedev <vinsanity305 at mail.ru<mailto:vinsanity305 at mail.ru>> wrote:

Dear molpro users.
We calculate ab initio potentials of alkali metal - inert gase weakly bound molecules.
Our research group uses def2-asvp,atzvp,aqzvp  basis sets for extrapolation to a complete basis set limit (2 and 3 point formulae from molpro manual-Lx,LHx,Ex2) .
But we stress, that these basis sets are not suitable for a 3-point extrapolation at all, because the lmax is the same for asvp and atzvp basis sets for Rb and Cs atoms:
For Cs:
def2-asvp
Library entry Cs   ECP ECP46MDF             selected for group  1
 Library entry CS     S def2-SVP             selected for orbital group  1
 Even tempered Cs S diffuse               selected for group 1    nprim= 1    centre=  0.005    ratio= 2.271    dratio= 1.000
 Library entry CS     P def2-SVP             selected for orbital group  1
 Even tempered Cs P diffuse               selected for group 1    nprim= 1    centre=  0.003    ratio= 5.198    dratio= 1.000
 Library entry CS     D def2-SVP             selected for orbital group  1
 Even tempered Cs D diffuse               selected for group 1    nprim= 1    centre=  0.008    ratio= 4.004    dratio= 1.000

def2-atzvp
Library entry Cs   ECP ECP46MDF             selected for group  1
 Library entry CS     S def2-TZVP            selected for orbital group  1
 Even tempered Cs S diffuse               selected for group 1    nprim= 1    centre=  0.005    ratio= 2.271    dratio= 1.000
 Library entry CS     P def2-TZVP            selected for orbital group  1
 Even tempered Cs P diffuse               selected for group 1    nprim= 1    centre=  0.003    ratio= 5.198    dratio= 1.000
 Library entry CS     D def2-TZVP            selected for orbital group  1
 Even tempered Cs D diffuse               selected for group 1    nprim= 1    centre=  0.004    ratio= 3.904    dratio= 1.000

For Rb:
def2-asvp
 Library entry Rb   ECP ECP28MDF             selected for group  2
 Library entry RB     S def2-SVP             selected for orbital group  2
 Even tempered Rb S diffuse               selected for group 2    nprim= 1    centre=  0.006    ratio= 2.320    dratio= 1.000
 Library entry RB     P def2-SVP             selected for orbital group  2
 Even tempered Rb P diffuse               selected for group 2    nprim= 1    centre=  0.003    ratio= 6.503    dratio= 1.000
 Library entry RB     D def2-SVP             selected for orbital group  2
 Even tempered Rb D diffuse               selected for group 2    nprim= 1    centre=  0.003    ratio= 8.238    dratio= 1.000

def2-atzvp
 Library entry Rb   ECP ECP28MDF             selected for group  1
 Library entry RB     S def2-TZVP            selected for orbital group  1
 Even tempered Rb S diffuse               selected for group 1    nprim= 1    centre=  0.006    ratio= 2.287    dratio= 1.000
 Library entry RB     P def2-TZVP            selected for orbital group  1
 Even tempered Rb P diffuse               selected for group 1    nprim= 1    centre=  0.006    ratio= 2.500    dratio= 1.000
 Library entry RB     D def2-TZVP            selected for orbital group  1
 Even tempered Rb D diffuse               selected for group 1    nprim= 1    centre=  0.003    ratio= 3.569    dratio= 1.000

So, a 3-point extrapolation is forbidden here, because we need at least 3 basis sets with different lmax (unfortunately, we have only two: atzvp,aqzvp).
--------------------------------------------------------------------------------------------------------------------------------------
Besides that, extrapolation formulae depend on the cardinal number n (which is the part of the basis set name - i.e. 2 for asvp, 3 for atzvp, 4 for aqzvp, and should be equal to the lmax). When we looked through output file, we noticed, that the same basis set has different lmax for different atoms:

For Cs (def2-aqzvp basis set with ecp46mdf)

 Library entry Cs   ECP ECP46MDF             selected for group  2
 Library entry AR     S def2-QZVP            selected for orbital group  1
 Even tempered Ar S diffuse               selected for group 1    nprim= 1    centre=  0.068    ratio= 2.441    dratio= 1.000
 Library entry AR     P def2-QZVP            selected for orbital group  1
 Even tempered Ar P diffuse               selected for group 1    nprim= 1    centre=  0.044    ratio= 2.497    dratio= 1.000
 Library entry AR     D def2-QZVP            selected for orbital group  1
 Even tempered Ar D diffuse               selected for group 1    nprim= 1    centre=  0.123    ratio= 2.407    dratio= 1.000
 Library entry AR     F def2-QZVP            selected for orbital group  1
 Even tempered Ar F diffuse               selected for group 1    nprim= 1    centre=  0.223    ratio= 2.440    dratio= 1.000
 Library entry AR     G def2-QZVP            selected for orbital group  1
 Even tempered Ar G diffuse               selected for group 1    nprim= 1    centre=  0.403    ratio= 2.500    dratio= 1.000

 Library entry CS     S def2-QZVP            selected for orbital group  2
 Even tempered Cs S diffuse               selected for group 2    nprim= 1    centre=  0.008    ratio= 1.465    dratio= 1.000
 Library entry CS     P def2-QZVP            selected for orbital group  2
 Even tempered Cs P diffuse               selected for group 2    nprim= 1    centre=  0.004    ratio= 2.468    dratio= 1.000
 Library entry CS     D def2-QZVP            selected for orbital group  2
 Even tempered Cs D diffuse               selected for group 2    nprim= 1    centre=  0.004    ratio= 2.911    dratio= 1.000
 Library entry CS     F def2-QZVP            selected for orbital group  2
 Even tempered Cs F diffuse               selected for group 2    nprim= 1    centre=  0.235    ratio= 2.500    dratio= 1.000

For Rb (def2-qzvp with ecp28mdf)

 Library entry Rb   ECP ECP28MDF             selected for group  2
 Library entry AR     S def2-QZVP            selected for orbital group  1
 Even tempered Ar S diffuse               selected for group 1    nprim= 1    centre=  0.068    ratio= 2.441    dratio= 1.000
 Library entry AR     P def2-QZVP            selected for orbital group  1
 Even tempered Ar P diffuse               selected for group 1    nprim= 1    centre=  0.044    ratio= 2.497    dratio= 1.000
 Library entry AR     D def2-QZVP            selected for orbital group  1
 Even tempered Ar D diffuse               selected for group 1    nprim= 1    centre=  0.123    ratio= 2.407    dratio= 1.000
 Library entry AR     F def2-QZVP            selected for orbital group  1
 Even tempered Ar F diffuse               selected for group 1    nprim= 1    centre=  0.223    ratio= 2.440    dratio= 1.000
 Library entry AR     G def2-QZVP            selected for orbital group  1
 Even tempered Ar G diffuse               selected for group 1    nprim= 1    centre=  0.403    ratio= 2.500    dratio= 1.000

 Library entry RB     S def2-QZVP            selected for orbital group  2
 Even tempered Rb S diffuse               selected for group 2    nprim= 1    centre=  0.006    ratio= 2.064    dratio= 1.000
 Library entry RB     P def2-QZVP            selected for orbital group  2
 Even tempered Rb P diffuse               selected for group 2    nprim= 1    centre=  0.005    ratio= 2.591    dratio= 1.000
 Library entry RB     D def2-QZVP            selected for orbital group  2
 Even tempered Rb D diffuse               selected for group 2    nprim= 1    centre=  0.003    ratio= 2.877    dratio= 1.000
 Library entry RB     F def2-QZVP            selected for orbital group  2
 Even tempered Rb F diffuse               selected for group 2    nprim= 1    centre=  0.341    ratio= 2.500    dratio= 1.000

So, def2-aqzvp basis set can change its cardinal number n, but it is still called aqzvp!
Does it mean, that we should use different n (i.e. cardinal numbers or lmax of a particular basis set) in the extrapolation formulae for the same basis set, if lmax changes?

So, it is impossible to extrapolate the energy of the system, which contains atoms with different lmax (when we use def2-anzvp
basis sets), because in such a case n is not determined (something like (n1+n2)/2 - which is not even an integer). Am I right?

I am also interested  in scientific papers, in which extrapolation to the complete basis set limit of def2-asvp/atzvp/aqzvp basis sets is carried out (if extrapolation is allowed for def2-anzvp basis sets).

Alexander Medvedev,
student of the 5th course of
Lomonosov Moscow State University
Department of Chemistry
Chair of Laser Chemistry

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