The spin-other-orbit contribution to the g-tensor is computed as suggested by Pickard and Mauri [15], with the modification for high-spin case, proposed by Patchkovskii and Schrekenbach [16]. The theory and implementation of this part of the code in the EPR module of the ADF package is explained in detail in [17].
The G(SOO) contribution is implemented for the all-electron case, only. The implementation uses a 6-dimensional numerical integration, and is therefore quite slow. However, it should still be possible to do 100 atoms or so with a TZP basis set, on a single-CPU PC.
Given the very small magnitude of the SOO corrections, it is rather unlikely that either the formal frozen core support, or a faster implementation will ever be done.
The term is activated by specifying SOO subsubkeyword within the EPRGT subkey of the EPR keyblock, ie:
CLGEPR
EprGTensor
SOO
SubEnd
END
Additionally, the following keywords (to be given at the top level of the EPR input file) can be used to controls certain technical aspects of the calculation:
NOGSOOSCREENING
This keyword will disable screening of the contributions in the 6D numerical integral. For large molecules (>20 atoms), this keyword will make the G(SOO) contribution scale as O(N**2) instead of O(N). It should not change calculated G(SOO) contributions by more than a few parts per million.
GSOODETAILED
Calculate and print contributions from (gauge-dependent) paramagnetic and diamagnetic currents. Using this option will defeat the screening to a large extent, and slow down the calculation.
GSOOSPINWEIGHTS w_alpha w_beta
Specifies the weights of the alpin-alpha and spin-beta currents, in the self-interaction corrected total current. For spin-doublet radicals, the default is "GSOOSPINWEIGHTS 0.0 2.0". Specifying "1.0 1.0" will disable self-interaction correction.
PROXCELLS number
Number of cells used for constructing proximity grid.
PROXBUF number
Size of the memory buffer (in 50-byte units) which will be used for sorting the proximity grid.
