Hi everyone,
I am trying to do some MC simulations for a hcp ternary system (A-B-C), I am confused about two things:
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Why do I need to set the chemical potentials range to scan for all three species A,B and C in the control.in file? From my understanding, for a multicomponent system with N species, only the chemical potentials of N-1 of N should be set then the left one will be determined automatically. So only the mu range of two species here needs to be set I think.
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I run two MC simulations at 1300K with different mu range set in control.in file. One is to scan mu A from 0 to -10 (case 1), the other is to scan mu A from 5 to -10 (case 2). The mu B and C of both cases are fixed to -10. After extracting the MC data of the mu A range from 0 to -10 (common area), I found the shape of the free energy surface of these two cases are exactly same, but these two surfaces have a gap of 5 between each other. In other words, for every single MC step with the same mu A, B and C, the free energy of case 2 is 5 higher than that of case 1. Why does the free energy shift a value that is equal to the difference of the starting point of the mu A range in these two control.in file? Is this due to that there is a reference in the memc2 code?
Any help would be much appreciated.