Charge equilibration for molecular dynamics simulations

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Charge equilibration (QEq) for molecular dynamics simulations [1] [2] is a technique for calculating the distribution of charges within a (large) molecule. This distribution can change with time to match changes in the local environment.

Electronegativity and electronic hardness[edit]

The atomic electronegativity is given by [3]

where IP is the ionisation potential, and EA is the electron affinity. The electronic hardness is given by [4]

Charge equilibration energy[edit]

Using the above expressions one has the following second order approximation for the total electrostatic energy ([2] Eq. 6)

The last term is a "shielded" Coulombic interaction, where

where represents a normalised ns Slater-type orbital.

Split-charge formalism[edit]


Fluctuating-charge formalism[edit]



See also[edit]