MOLPRO

40 SPIN-ORBIT-COUPLING 293
LS
ALS
FLS
AFLS|AMFI
ECPLS
Standard spin-orbit calculations.
The one-center approximation is used for one- and two-electron spinorbit
integrals.
The effective Fock-matrix approximation is used for the internal part
too.
The one-center approximation is used for one- and two-electron spinorbit
integrals, and the effective Fock-matrix approximation for the
internal part.
Effective core potentials are used for all atoms at which they are defined;
contributions of all other atoms are neglected (see below).
In case that the effective Fock matrix is used for all contributions, and no spin-orbit integrals
are pre-calculated and stored on disk (i.e., the LSINT command is not given), the Fock matrices
are evaluated in direct mode and no integrals are stored on disk. When this is combined with
the one-center approximation (AMFI), the computing and I/O times are drastically reduced, and
this makes spin-orbit calculations quite fast even for larger molecules.
Also, the treatment of ECP-type of spin-orbit interaction has been changed and now allows
for treating both ECP and non-ECP atoms in one calculation. Thus, in molecules containing
both heavy and light atoms, the heavy atoms can be described using ECPs and the light atoms
using all-electron basis sets. If the operator type is LS, ALS, FLS, or AFLS, then for the atoms
having an ECP spin-orbit operator defined in the basis input the ECP operator is used, while
the full BP-operator is used for all other atoms (couplings are neglected). Both one-center and
AMFI approximations can be used in this case. If, on the other hand, one specifies the operator
type as ECPLS, then the behavior is the same as in the previous versions, i.e., only the ECP
contributions are considered and the contributions from all other atoms are neglected.
40.5 Calculation and diagonalization of the entire SO-matrix
HLSMAT,type, record1, record2, record3, . . .
Computes the entire SO matrix and diagonalizes it using all states which are contained in the
records record1, record2, record3, . . . . All records must have been generated using the SAVE
directive of the MRCI program. type may be either LS for Breit-Pauli calculations, or ECP for
ECP-LS calculations. By default, the eigenvalues and dipole transition matrix elements between
the ground and excited states are printed.
As with the TRANLS card, the HLSMAT is recognized only by the MRCI program and must be
preceded by a CI card. Also, the OCC and CLOSED cards must be the same for all states used
in a HLSMAT calculation.
40.6 Modifying the unperturbed energies
Often it may be sufficient to compute the spin-orbit matrix elements in a smaller basis or at a
lower computational level than the energies. It is therefore possible to replace the energy eigenvalues
by precomputed values, which are passed to the spin-orbit program by the MOLPRO
variable HLSDIAG. The energy values in HLSDIAG must be in exactly the same order as the
states in the records given on the HLSMAT card. Before any spin-orbit calculation, the variable
HLSDIAG must either be undefined or cleared (then the original energies are used), or must contain
exactly the number of energies as the number of states treated in the subsequent spin-orbit
calculation (use CLEAR,HLSDIAG to clear any previous values in the variable). It is the user’s
responsibility that the order of the energies in HLSDIAG is correct!