*TRANSFORMATION  

Purpose:

Transformation  of two-electron integrals  to molecular orbital basis .

.FINAL LEVEL  

READ (LUINP,*) ITRFIN
Final integral transformation  level (only active if the keyword ".INTERFACE  " has been specified, or this is an ABACUS  or RESPONSE  calculation.

.LEVEL  

READ (LUINP,*) ITRLVL
Integral transformation level (see comments).

.OLD TRANSFORMATION  

Use existing transformed integrals

.PRESORTED  

Indicacates that the transformed two-electron integrals are already present generated through the keyword .SORT I   in the **INTEGRALS   input module.

.PRINT  

READ (LUINP,*) IPRTRA
Print level in integral transformation module

.RESIDENT MEMORY  

READ (LUINP,*) MWORK
On virtual memory computers, the transformation will run more efficiently if it can be kept within the possible resident memory size: the real memory size. SIRIUS will attempt to only use MWORK double precision words in the transformation.

Comments:

There are several types of integral transformations which may be specified by the two transformation level keywords.

0:

CI calculations, MCSCF gradient (default if CI, but no MCSCF specified). One index all orbitals, three indices only active orbitals.

1:

Obsolete, do not use.

2:

Default for MCSCF optimization. All integrals needed for SIRIUS second-order MCSCF optimization, including the integrals needed to explicitly construct the diagonal of the orbital hessian. Two indices occupied orbitals, two indices all orbitals, with some reduction for inactive indices. Both (cd/ab) and (ab/cd) are stored.

3:

Same integrals as 2, including also the (ii/aa) and (ia/ia) integrals for exact inactive-secondary diagonal elements of the orbitals Hessian.

4:

All integrals with minimum two occupied indices.

5:

3 general indices, one occupied index. Required for MP2 natural orbital analysis (the MP2 module automatically performs an integral transformation of this level).

10:

Full transformation.