A New Semiempirical Approach to Study Ground and Excited States of Metal Complexes in Biological Systems

Abstract

In this paper we develop a "diatomic in molecules semiempirical ligand field" (DIMSELF) method to calculate ground and excited many-body potential energy surfaces for an arbitrary transition metal ion in an arbitrary complex system. This method is not restricted to a high-symmetry environment and is meant to be inexpensive and suitable for nonadiabatic excited states dynamics on-the-fly. Within the approximations employed, the method includes full CI (configuration interaction) and SO (spin-orbit) interactions, essential to the description of nonradiative transitions such as those of myoglobin in the presence of carbon monoxide. We test our method against high level ab initio calculations for a simple model system of myoglobin's heme pocket. Finally, we discuss our results and compare with previous calculations in the literature.

QM/MM methods: Looking inside heme proteins biochemisty

“…We found that there is a transition from a six coordinated singlet ligated species into a quintet five coordinated heme. In a previous work, using time dependent DFT and a diatomic in molecules semiempirical approach, we observed multiple crossing of quintet and triplet excited states along the carbon monoxide deligation coordinate [61]. The QM/MM energy profiles also indicate a very close proximity of these two spin states.…”

Variations ofg-tensor principal values in reduced [2Fe−2S] cluster of iron-sulfur proteins

“…Thus, the authors of ref. 25 were able to develop the so-called "diatomic in molecules semiempirical ligand field" method to calculate ground and excited many-body potential energy surfaces for an arbitrary transition metal ion in ah arbitrary complex system. This method is inexpensive, not restricted to a highsymmetry environment, suitable for nonadiabatic excited states dynamics on-thefly, and includes full configuration and spin-orbit interactions.…”

Potential energy surfaces and dynamics of Ni2+ ion aqueous solution: Molecular dynamics simulation of the electronic absorption spectrum

“…Recently, Margulis et al 16 developed such a model, called diatomic in molecules semiempirical ligand field method, and applied it to calculate the potential energy curves for a simple model system of myoglobin heme pocket. Recently, Margulis et al 16 developed such a model, called diatomic in molecules semiempirical ligand field method, and applied it to calculate the potential energy curves for a simple model system of myoglobin heme pocket.…”