title: Density functional theory/molecular mechanics approach for electronic g-tensors of solvated molecules.
abstract: A general density functional theory/molecular mechanics approach for computation of electronic g-tensors of solvated molecules is presented. We apply the theory to the commonly studied di-tert-butyl nitroxide molecule, the simplest model compound for nitroxide spin labels, and explore the role of an aqueous environment and of various approximations for its treatment. It is found that successive improvements of the solvent shift of the g-tensor are obtained by going from the polarizable continuum model to discrete solvent models of various levels of sophistication. The study shows that an accurate parametrization of the electrostatic potential and polarizability of the solvent molecules in terms of distributed multipole expansions and anisotropic polarizabilities to a large degree relieves the need to explicitly include water molecules in the quantum region, which is the common case in density functional/continuum model approaches. It is also shown that the local dynamics of the solvent around the solute significantly influences the electronic g-tensor and should be included in benchmarking of exchange-correlation functionals for evaluation of solvent shifts of g-tensors. These findings can have important ramifications for the use of advanced hybrid density functional theory/molecular mechanics approaches for modeling spin labels in solvents, proteins, and membrane environments.
authors: Department of Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, Stockholm, Sweden. rinkevic@theochem.kth.se
authors: Zilvinas
authors: Z
authors: Rinkevicius
authors: N Arul
authors: NA
authors: Murugan
authors: Jacob
authors: J
authors: Kongsted
authors: Kestutis
authors: K
authors: Aidas
authors: Arnfinn Hykkerud
authors: AH
authors: Steindal
authors: Hans
authors: H
authors: Agren
mesh_terms: D056004:Molecular Dynamics Simulation; D009589:Nitrogen Oxides / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D009589:Nitrogen Oxides; C522822:tert-butylnitroxide