Hi,
what you write is correct. It appears to me on first glance that you have
encountered a bug in applying dvdl_norest. In thermo_int.f the restraint
energy on process V0 is subtracted from dvdl. I guess since we want to
subtract the restraint energy from V0, which enters dvdl as V1-V0, that
should be a plus instead. Embarrasing error :-(
Try and change line 27 of thermo_int.f from
dvdl = dvdl - ecopy(32)
to
dvdl = dvdl + ecopy(32)
recompile and rerun a short simulation. You should get a dvdl that is
indeed equal to VDWAALS in your case.
The reason this remained undetected is that few people used the
functionality and the restraint contribution is small enough so that in my
test cases, I still got reasonable results as compared to experiment... If
that turns out all right, I will put together a bug fix.
Thanks for noticing (and apparently being the only one using that part of
the code),
Thomas
Dr. Thomas Steinbrecher
BioMaps Institute
Rutgers University
610 Taylor Rd.
Piscataway, NJ 08854
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Received on Wed Feb 24 2010 - 08:00:04 PST
