X ray spectra simulations of transition metal metals using core RAS method
For complexes include spin orbital coupling, open shell states and degeneracy, a higher level method is desired. One such class of methods is muti-congurational self consistent field (MCSCF), among which the most widely adopt method is restricted active space self consistent field (RASSCF), choosing most important orbitals in active space, not only the metal character 3d molecular orbitals (MOs), but also the important ligand MOs. Core hole-electron correlation could be described accurately by interpretation and assignment for each individual transition which contributes to the spectrum using the core RAS method. All the calculations have been performed with MOLCAS 7.9. The active space could be designated as RAS(l, m, n; i, j, k), where i, j, and k are the number of orbitals in RAS1, RAS2, and RAS3 spaces respectively, l is the total number of electrons in the active space, m the maximum number of holes allowed in RAS1, and n the maximum number of electrons in RAS3. In our calculation, the metal character 3d orbital and orbitals strongly correlate with them, such as the bonding and anti-bonding partners, are all included in RAS2.