lammps手册里面有讲lj单位约化
http://lammps.sandia.gov/doc/units.html
可以参考一下,应该都差不多
mass = mass or m
distance = sigma, where x* = x / sigma
time = tau, where tau = t* = t (Kb T / m / sigma^2)^1/2
energy = epsilon, where E* = E / epsilon
velocity = sigma/tau, where v* = v tau / sigma
force = epsilon/sigma, where f* = f sigma / epsilon
temperature = reduced LJ temperature, where T* = T Kb / epsilon
pressure = reduced LJ pressure, where P* = P sigma^3 / epsilon
viscosity = reduced LJ viscosity, where eta* = eta sigma^3 / epsilon / tau
charge = reduced LJ charge, where q* = q / (4 pi perm0 sigma epsilon)^1/2
dipole = reduced LJ dipole, moment where *mu = mu / (4 pi perm0 sigma^3 epsilon)^1/2
electric field = force/charge, where E* = E (4 pi perm0 sigma epsilon)^1/2 sigma / epsilon
另外,陈正隆的书里面有个一两页是讲LJ约化的,讲的比较简单,在前面的几章中,你自己找找吧,关于陈正隆的书,论坛上有电子版的下载
http://www.mdbbs.org/thread-1620-1-1.html