An improved model electronic Hamiltonian for potential energy surfaces and spin-orbit couplings of low-lying d-d states of [Fe(bpy)3]2+.

With the aim of exploring excited state dynamics, a model electronic Hamiltonian for several low-lying d-d states of [Fe(bpy)3](2+) complex [S. Iuchi, J. Chem. Phys. 136, 064519 (2012)] is refined using density-functional theory calculations of singlet, triplet, and quintet states as benchmarks. Spin-orbit coupling elements are also evaluated within the framework of the model Hamiltonian. The accuracy of the developed model Hamiltonian is determined by examining potential energies and spin-orbit couplings at surface crossing regions between different spin states. Insights into the potential energy surfaces around surface crossing regions are also provided through molecular dynamics simulations. The results demonstrate that the constructed model Hamiltonian can be used for studies on the d-d excited state dynamics of [Fe(bpy)3](2+).