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

[Grant Hill]

Dear Sasha,

The def2 series of basis sets was not designed to systematically approach the basis set limit, so the standard extrapolation formulae are not really expected to work here (although I see no reason why Molpro should stop you trying - GIGO). There may be some more appropriate formulae in the literature, but I am not aware of them.


On 23 Oct 2013, at 13:17, sasha medvedev <vinsanity305 at mail.ru> wrote:

> 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:

This is entirely expected. Think of a minimal basis for a first row element (C) and one for a transition metal (Ti), lmax must be different simply to construct the occupied orbitals. One approach when using correlation consistent sets is to keep lmax as the largest for the system (usually the heaviest element) - meaning cardinal number + 1 in this case. A lack of high accuracy reference data means this isn't particularly well tested, but it _seems_ to work.

Best regards,

Grant