Individual spin-orbit matrix elements can be computed within the MRCI program using

`TRANLS`,*record1.file, record2.file, bra2ms, ket2ms, lsop*;

where

*record1.file*- Record holding the bra-wavefunction.
*record2.file*- Record holding the ket-wavefunction.
Both records must have been generated using the
`SAVE`directive of the MRCI program. *bra2ms*- value of the bra-wavefunction.
*ket2ms*- value of the ket-wavefunction.
*lsop*- Cartesian component of the Spin-orbit Hamiltonian.

This can be one of , , or in all electron calculations, and , , or in ECP calculations. Starting from the MOLPRO version 2008.1, more types are available which control the approximation level. These are described in section 44.4.

Since the spin-orbit program is part of the MRCI program,
the `TRANLS` card must be preceded by a `[MR]CI` card.
For the case that the matrix elements are computed for MCSCF wavefunctions,
one has to recompute and save the CI-vectors using the MRCI program (see chapter 20),
using the `NOEXC` directive to avoid inclusion of any further excitations out
of the MCSCF reference function. If in the MRCI step several states of the same symmetry are
computed simultaneously using the `STATE` directive, the matrix elements are computed for
all these states. Note that the `OCC` and `CLOSED` cards must be the same for all states
used in a `TRANLS` calculation.

The selection rules for the values are
for the `LSX` and `LSY` operators,
and for the `LSZ` operator. Note that has to be specified, and so
the selection rules applying to the difference of the input values are 0 or 2.

In all-electron SO calculations the value of the calculated spin-orbit matrix element is saved
(in atomic units) in the MOLPRO variables `TRLSX`, `TRLSY` and `TRLSZ`
for the , , and components respectively.
For ECP-LS calculations the variables `TRECPLSX`, `TRECPLSY`, and `TRECPLSZ` are used.
Note that for imaginary matrix elements (i.e., for the and components of the SO Hamiltonian)
the matrix elements are imaginary and the stored real values have to be multiplied by .
If matrix elements for several states are computed, all values are stored in the respective
variable-arrays with the bra-states running fastest.

molpro@molpro.net 2018-10-21