Restrained Electrostatic Potential
The following codes are available:
resp/espfit.py: The restrained electrostatic potential (RESP) fitting procedure.
resp/driver.py: Driver of the code.
test_resp_1: Example for two-stage charge fitting for one conformer.
test_resp_2: Example for two-stage charge fitting for two conformers.
RESP charges result from fitting the classical electrostatic potential (ESP) generated by atom-centered point charges to the quantum ESP computed outside the van der Waals surface of the molecule. The fitted charges are restrained by a hyperbolic term, which requires an iterative fitting procedure to compute the charges.
The charges (q) are computed by solving the following equation:
A q = B.
The left-hand side contains the information about the classical ESP while the right-hand side contains information about the quantum ESP. A hyperbolic restraint term that depends on the charges is added to the diagonal elements of matrix A. The charges and the diagonal elements of A are changed iteratively until the charges converge.
- [Bayly:93:10269-10280] C. I. Bayly et. al. J. Phys. Chem. 97, 10269 (1993)