Hello, dear amber developers,
When I want to print the pressure in NVT simulations by the pmemd.MPI (Amber18),
I found that the pressure calculation is expressed as (runmd.F90 script):
……..
if (need_virials) then
press(m) = (pconv + pconv) * (ekcmt(m) - virial(m)) / si(si_volume)
si(si_tot_press) = si(si_tot_press) + press(m)
……….
I do not understand the meaning of (pconv + pconv) in the above expression. In my view, the developer want to do this:
press(m) = (pconv + pconv) * (ekcmt(m) - virial(m)) / si(si_volume)
-> press(m) = 2* pconv * (ekcmt(m) - virial(m)) / si(si_volume)
-> press(m) = pconv * (2*ekcmt(m) -2* virial(m)) / si(si_volume)
The 2*ekcmt = total (m^2v^2) has no problem, while the 2*virial(m) means what ?
Th virial term have been multipled by 0.5 in the pme_force.F90 script, then here multiple by a factor of 2, so I can consider it unchange and it equals to addition of all i-j pair-potential. The overlap calculation happen? I search the pressure-calculation reference and the result only involve half of all i-j pair-potential. it is a bug or other reason?
Thank you !
_______________________________________________
AMBER mailing list
AMBER.ambermd.org
http://lists.ambermd.org/mailman/listinfo/amber
Received on Sun Aug 09 2020 - 21:30:02 PDT
