| 摘要 |
Molecular modeling techniques can be improved and their speed increased by a new analytical approach to the determination of the effective Born radii of atoms in a molecule. In this approach, the electrical polarization component of solvation energy of an atom i is approximated as the electrical polarization energy given by the classical Born equation (Eq. 2), assuming that the Born radious alpha is equal to the van der Waals radius of the atom, minus the effects of all surrounding atoms, j, which displace solvent from around atom i. This displacement effect increases with the volume of the atom j and decreases as the fourth power of the separation between atom i and atom j. Epol for atom i can therefore be calculated using the following equation: Epol,i = -166 (1-1/ epsilon )qi [1/(P0+Ri)- SIGMA PVj/rij<4>], wherein Ri is the van der Waals radius of atom i, Vj is the volume of an atom j, an P0 and P are empirically determined, solvant-dependant constants or functions of rij. This value of Epol,i is then substituted into a rearranged form of the Born equation: alpha i = -166 (1-1/ epsilon ) qi<2>/Epol,i to give the effective Born radius for atom i, alpha i, for use in the generalized Born equation. |
