Although I haven't extensively used = FF calculations, I used Tinker for some tautomer/isomer search. Molden = http://www.cmbi.ru.nl/molden/ = can generate everything you need.

Davor = Sakic

Department of General and Inorganic = Chemistry
Faculty of Pharmacy and Biochemistry, www.pharma.hr
University of = Zagreb
Ante Kovacica 1
10000 = Zagreb
Croatia
davor.sakic||gmail.com
dsakic||pharma.hr

On 11. sij. 2011., at 05:34, Alavi, Saman = Saman.Alavi!A!nrc-cnrc.gc.ca wrote:

Hi = Aaron,

You may want to look at DL_FIELD which is a new utility = for constructing the FIELD file for use in DL_POLY. It is free of charge = and only requires registration.

An alternative is to use the AMBER "antechamber" = program to determine the atom types, count (and list) = bounds between the atoms (and harmonic force constants between = them,) angles and harmonic angle bend harmonic force constants, = dihedrals (proper and improper) along with the related = parameters, etc. according to the AMBER force field functions. = Parameters for many types of potential (including OPLS) are = available in AMBER. Once you get the list of bonds, angles, dihedrals = > from the antechamber program, it is a much easier task to prepare the = DL_POLY FIELD file. I can send a more detailed description of the = procedure if you have access to AMBER and antechamber.

I hope this = helps.

Best regards,
Saman Alavi

From: owner-chemistry+saman.alavi=3D= =3Dnrc.ca{:}ccl.net [owner-chemistry+saman.alavi=3D=3Dnrc.ca{:}ccl.net] = On Behalf Of Deskins, N Aaron nadeskins++WPI.EDU = [owner-chemistry{:}ccl.net]
Sent: January-10-11 9:29 = AM
To: Alavi, = Saman
Subject: CCL: Force field = calculations-getting started

Hello fellow CCL=92ers,

  I find = myself increasingly in need of running some force field calculations = (e.g. OPLS) for organic/biological molecules, and am looking for the = best way to get started. I come from an electronic structure background = where making an input file is pretty straight-forward. Choose atomic = coordinates (xyz), basis set, methodology, and run the = calculation.

  Setting = up an input file for the various molecular mechanics methods however = seems more complicated. You can start with the xyz atomic coordinates, = but you also have to worry about various atom types for the same = element, atom connectivity, etc.

Can anyone suggest = some software/website/tutorial that would help in setting up an input = file?

  I=92m leaning towards using = DL_POLY (I have experience with this code for =91simpler=92 systems) = with the OPLS force field, but this isn=92t set in stone. OPLS seems to = be widely used for the types of molecules I=92m interested in = (organics).

Thank you,

Assistant Professor
Worcester Polytechnic = Institute
Worcester, MA