updating coordinates using IMD

From: David E. Konerding (dekonerding_at_lbl.gov)
Date: Wed Nov 26 2003 - 14:09:10 CST


I am interested in using IMD, I've gone through the code and managed to
write a simple Python extension (yes, I know about the python IMD
wrappers, but
I wanted a pure python version). It works OK in most cases, although I
find that the NAMD side is a bit flaky; sometimes it disconnects telling
me my
VMD version number is too old. When it does work I can collect forces
and energies.

I have a few questions:

1) Is the IMD socket protocol truly asynchronous: the read and write
messages are totally distinct from each other (I'm more accustomed to
call/response style

2) IMD doesn't seem to have any support for changing the coordinates
directly and getting an energy evaluation. IE, I want to NAMD to remain
paused, I update all atomic coords to new ones, get back the energy
given those coords,
and NAMD goes back to a paused state.

My thinking was to add a new message, IMD_COORDS, which the client could
send to NAMD and update the coordinates. Then, another message,
IMD_GO_ONCE, would cause NAMD to evaluate forces/energies, send one
IMD_ENERGIES and one IMD_FCOORDS, and return to paused.

Does this seem reasonable?

This archive was generated by hypermail 2.1.6 : Wed Feb 29 2012 - 15:37:09 CST