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

Abstract

We develop a model effective Hamiltonian for describing the electronic structures of first-row transition metals in aqueous solutions using a quasidegenerate perturbation theory. All the states consisting of 3d(n) electronic configurations are determined by diagonalizing a small effective Hamiltonian matrix, where various intermolecular interaction terms such as the electrostatic, polarization, exchange, charge transfer, and three-body interactions are effectively incorporated. This model Hamiltonian is applied to constructing the ground and triplet excited states potential energy functions of Ni(2+) in aqueous solution, based on the ab initio multiconfiguration quasidegenerate perturbation theory calculations. We perform molecular dynamics simulation calculations for the ground state of Ni(2+) aqueous solution to calculate the electronic absorption spectral shape as well as the ground state properties. Agreement between the simulation and experimental spectra is satisfactory, indicating that the present model can well describe the Ni(2+) excited state potential surfaces in aqueous solution.

A model electronic Hamiltonian to describe low‐lying d–d and metal‐to‐ligand charge‐transfer excited states of [Fe(bpy)3]2+

“…This modeling is based on an idea that the EX interaction originates from an electron exchange within a Slater determinant. [ 27 ] In the present extended model Hamiltonian, the EX matrix elements do not appear in the blocks 3 and 4. In addition, the orbitals are not included in Equation ) even for the block 2.…”

“…H CT matrix elements: By employing the same idea as in the previous studies, [18,27] the CT configurations from the bpy occupied σ orbitals to the Fe 2+ unoccupied 3d/4s orbitals are considered. Thus, the form of the CT matrix elements in the block 1 is the same as that of the previous model Hamiltonian, [19] as presented in the Supporting Information.…”

Intruder states in multireference perturbation theory: The ground state of manganese dimer

“…Most of them employ a real or imaginary shift operator that modifies the zeroth‐order energies of the reference or intermediate states and leads to a modified second‐order energy correction given by where Δ is a shift parameter that may depend on k . Intruder state removal shift techniques are available in most of quantum chemistry packages22–24 and are conventionally used to ensure smooth character of the calculated potential energy surfaces 25–39. It is important to stress here that the shift techniques are not a panacea for all problems originating from a selection of poor partitioning in MRPT.…”

A quantum chemical model for a series of self-assembled nanocages: the origin of stability behind the coordination-driven formation of transition metal complexes up to [M12L24]24+

“…In this section, we present a summary of the computational methods used by our model. First, the effective model Hamiltonian developed previously 17,18 and the present extension are described. Second, we briefly describe the GB method and the Hawkins' pairwise approximation [23][24][25] to obtain reasonable effective Born radii of palladium(II) complexes.…”

“…The second term represents the CT to 5s orbitals, which can be also modelled by the overlap integrals as in the first term by using the 5s orbitals. 17 However, this term contributes only to the diagonal elements, and thus, a simpler modelling by using the Morse potential was employed. 18,42 E 0 CT , k CT , and R 0 CT are adjustable parameters.…”