Surprising change in the definition of AVxZ basis sets for 2nd row elements

[tibo...@gmail.com]

Dear developers,

I have discovered that recent versions of Molpro interpret AVxZ to mean AVxZ+d for second row elements, while the non-abbreviated form of the same basis sets does not include the tight-d functions by default.

Test results:

1. Molpro 15 basis=aug-cc-pVDZ
   Library entry SI     S aug-cc-pVDZ          selected for orbital group  1
2. Molpro 15 basis=AVDZ
   Library entry SI     S aug-cc-pVDZ          selected for orbital group  1
3. Molpro 23 basis=aug-cc-pVDZ
   Library entry SI     S aug-cc-pVDZ          selected for orbital group  1
4. Molpro 23 basis=AVDZ
   Library entry SI     S aug-cc-pv(d+d)z      selected for orbital group  1

As you can see, AVDZ used to mean exactly the same as aug-cc-pVDZ, but now AVDZ is interpreted to be AVDZ+d. This change in behavior has happened sometime between Molpro 2015 and 2022.3.

Was this change intentional? I could not find any mention of it in the release notes, and it is a surprising change in behavior.

Best wishes,

Tibor Győri