Charge transfer effective Hamiltonians

In the EH-CSD approach it is not convenient to decouple electrostatic terms into rigid Coulombic and polarization contributions the effective Hamiltonian leads to compute these two terms together. Exchange repulsive terms are hardly computed when the second partner of the interaction is a liquid they may be obtained with delicate simulation procedures, and it is convenient to decouple them into two contributions, namely the work spent to form a cavity of a suitable shape and an additional repulsion contribution. Dispersion contributions may be kept we shall examine this term in more detail later. Charge-transfer contributions are damped in liquids their inclusion could introduce additional problems in the definition of Vjnt via continuous solvent distributions. It is advisable to neglect them, as it is done in the interaction potentials used in simulations with the present approach it is possible to describe the charge transfer effect by enlarging the solute M —> M-Sn. 

Consideration of the spin-orbit interaction and the effect of an external magnetic field on the electronic ground state of an ion in a CF allows evaluation of the various terms in the spin-Hamiltonian of Equation (31). In addition, the interaction of the nucleus of the paramagnetic ion and ligand nuclei with the d-electron cloud must be considered. In this way the experimentally determined terms of the spin-Hamiltonian may be related to such parameters as the energy differences between levels of the ion in the CF and amount of charge transfer between d-electrons and ligands. 

Rate constant for charge transfer between donor and acceptor Effective coupling between donor and acceptor states Matrix element of Hamiltonian between diabatic donor and acceptor states... 

The applicability of LFDFT, like LFT itself, is rooted in an effective hamiltonian theory that states that, in principle, it is possible to define precisely a hamiltonian for a sub-system such as the levels of a transition metal in a transition-metal complex or a solid. This condition is possible, because in Wemer-type complexes the metal-ligand bond is mostly ionic and as such allows one to take a spectroscopically justified preponderant electronic d" or f" configuration as well defined ligand-to-metal and metal-to-ligand charge-transfer states are well separated from excitations within this configuration. 

The charge transfer contribution CT may play an important role in some chemical processes. Intuitively, this term corresponds to the shift of some electronic charge from the occupied orbitals of a monomer to the empty orbitals of the other. In the variational decomposition schemes this effect can be separately computed by repeating the calculations on the dimer with deletion of some blocks in the Hamiltonian matrix of the system and tak-... 

With the Born-Oppenheimer approximation and assuming that there is no charge transfer between regions, the effective Hamiltonian of the system can be separated into three terms ... 

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