Multiconfigurational linear response MCLR

Ab initio determinations of SOC in carbene (1) have been carried out for three bond angles (0 = 90, 112 and 135°) by McKellar et al. [27J using SCI and SDCI wave functions and by Vahtras et al. [19] for the equilibrium geometry employing a multiconfiguration linear response (MCLR) approach. Both sets of calculations are based on the full coupling operator with the... 

The linear response methods offer a viable alternative to the Cl procedure [38]. A time-dependent (TD) perturbation theory (e.g. involving an oscillating electric field), combined with the SCF or MCSCF method is referred to as the TD-SCF (or random phase approximation, RPA) or the TD-MCSCF (or multiconfigurational linear response, MCLR), respectively. Let us consider the time development of the dipole moment (z-component for simplicity) ... 

The use of multiconfiguration linear response (MCLR) theory is another approach to the calculation of spin-spin coupling interactions. As is usual for ab initio MO calculations, the results obtained are found to be basis set dependent. In general, satisfactory agreement with the available experimental data is achieved. 

AIMD = ab initio molecular dynamics B-LYP = Becke-Lee-Yang-Parr CCSD = coupled cluster single double excitations CVC = core-valence correlation ECP = effective core potential DF = density functional GDA = gradient corrected density approximation MCLR = multiconfigurational linear response MP2 = M0ller-Plesset second-order (MRD)CI = multi-reference double-excitation configuration interaction RPA = random phase approximation TD-MCSCF = time-dependent multiconfigurational self-consistent field TD-SCF = time-dependent self-consistent field. 

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