<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>Hi,</div><div><br></div><blockquote type="cite">I noticed that there're charmm27 force field files in Gromacs-4.0.5 software package. <br>But charmm27 force field can't be choosed in pdb2gmx. So can I use <br>charmm27 force field in Gromacs now?<font class="Apple-style-span" color="#000000"><font class="Apple-style-span" color="#144FAE"><br></font></font></blockquote><br><div>The files are there unofficially (that's why they're not included in the ff.dat file) and in an old version. You could try out the charmm27 parameters with CMAP support by downloading the latest version of the source code in git master and use the latest files, which I can provide you with (send an e-mail to me and I'll give them to you). The CHARMM ff (for proteins and lipids at least) will be officially supported in upcoming Gromacs version 4.1.</div><div><br></div><div>Regards,</div><div>Pär Bjelkmar</div></body></html>