<P> Hello,I want to use spc216.gro and apply the tip3p.itp parameters, but it would make a mistake for the pre-processor "grompp" ,it said can't find HW atomtypes, the force file which I used is "<SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: 'Times New Roman'; mso-bidi-font-size: 12.0pt; mso-fareast-font-family: ËÎÌå; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">ffG<?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" /><st1:chmetcnv w:st="on" UnitName="a" SourceValue="43" HasSpace="False" Negative="False" NumberType="1" TCSC="0">43a</st1:chmetcnv>1.itp". my tip3p.itp file is as follows:</SPAN> </P>
<P> <EM>[ moleculetype ]<BR>; molname nrexcl<BR>SOL 2</EM></P>
<P><EM>[ atoms ]<BR>; id at type res nr residu name at name cg nr charge<BR>#ifdef _FF_OPLS<BR>1 opls_111 1 SOL OW 1 -0.834<BR>2 opls_112 1 SOL HW1 1 0.417<BR>3 opls_112 1 SOL HW2 1 0.417<BR>#endif<BR>#ifdef _FF_CHARMM<BR>1 OT 1 SOL OW 1 -0.834<BR>2 HT 1 SOL HW1 1 0.417<BR>3 HT 1 SOL HW2 1 0.417<BR>#endif<BR>#ifdef _FF_GROMACS <BR>1 OWT3 1 SOL OW 1 -0.834<BR>2 HW 1 SOL HW1 1 0.417<BR>3 HW 1 SOL HW2 1 0.417<BR>#endif<BR>#ifdef _FF_GROMOS96<BR>1 OWT3 1 SOL OW 1 -0.834<BR>2 HW 1 SOL HW1 1 0.417<BR>3 HW 1 SOL HW2 1 0.417<BR>#endif</EM></P>
<P><EM>#ifdef FLEXIBLE<BR>[ bonds ]<BR>; i j funct length force.c.<BR>1 2 1 0.09572 502416.0 0.09572 502416.0 <BR>1 3 1 0.09572 502416.0 0.09572 502416.0 <BR> </EM></P>
<P><EM>[ angles ]<BR>; i j k funct angle force.c.<BR>2 1 3 1 104.52 628.02 104.52 628.02 </EM></P>
<P><EM>#else<BR>[ settles ]<BR>; i j funct length<BR>1 1 0.09572 0.15139</EM></P>
<P><EM>[ exclusions ]<BR>1 2 3<BR>2 1 3<BR>3 1 2<BR>#endif</EM></P>
<P>the version of the gromacs is 4.0.5.</P>
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<P>Thank you for all your help !</P>
<P> </P>