# particel insertion method

Hi:
I am doing a simple calculation on the solvation energy of lipid head
groups in the
membrane--protein system, and would be interested if some one could tell me
where to find some
basic references for the particle insertion method for free energy calculation.
The method that I
am using for the free energy (mostly due to electrostatic interactions ) is the
following: perform a
simulation 1 for the system with charge set A, and perform another
simulation 2 with charge set
B. Then, calculate the energy difference of changing the charges from A to B
using trajectories
from simulation 1 to obtain e1 (A->B), and similarly calculate the energy
difference using
trajectory 2 e2(A->B). Finally, calculate the free energy from the
average of these two. I
wonder whether anybody has used this kind of method before and whether this is a
reasonably
accurate method to use for solvation energy calculations.
I will collect the information I get and post a summary. Thanks.
Feng