Hi,
I try to use compute ti to calculate the free energy.
I used a small system to check this command. I put some particles into a box which have a wall across the box.
The box is cut into two regimes. Particles are stay in one regime. And then i remove the wall, they go around inside the box.
I want to get the free energy change after the wall is removed. Theoretical approximation of the free energy change is : F(no wall)=ln2 F(wall).
But i found the free energy is totally the same. The main input file is posted here:
pair_coeff * * 0.5 3.0 3.36
variable flambda equal 0.1
variable dflambda equal 1
fix 4 all adapt 1 pair lj/cut epsilon * * v_flambda scale no reset yes
compute 1 all ti lj/cut v_flambda v_dflambda
thermo_style custom step temp press etotal pe ke c_1
…
I use f(lambda)=lambda . So the lambda value is changed from 0 to 1.
So what is wrong with my calculation?? Any help is appreciated! Thanks!
Suzan