Dear,<BR>My&nbsp;receptor&nbsp;is&nbsp;membrane&nbsp;proteins,then&nbsp;I&nbsp;get&nbsp;protein-ligand&nbsp;complex.I&nbsp; want&nbsp;to&nbsp;do&nbsp;MD&nbsp;simulations&nbsp;in&nbsp;DPPC.I&nbsp;use&nbsp;the&nbsp;GROMOS96&nbsp;53a6&nbsp;force&nbsp;&nbsp;<BR>&nbsp;field&nbsp;modified&nbsp;in&nbsp;order&nbsp;to&nbsp;include&nbsp;Berger¡¯s&nbsp;parameters&nbsp;for&nbsp;lipids .The&nbsp;topology&nbsp;for&nbsp;the&nbsp;ligand&nbsp;was&nbsp;created <BR>employing&nbsp;the&nbsp;server&nbsp;PRODRG&nbsp;2.5&nbsp;Beta.<BR>When I&nbsp;finished&nbsp;the&nbsp;command&nbsp;"perl&nbsp;inflategro.pl&nbsp;system.gro&nbsp;4&nbsp;DPPC&nbsp;14&nbsp;system_inflated.gro&nbsp;5&nbsp;area.dat",<BR>&nbsp;I&nbsp;want&nbsp;to&nbsp;run&nbsp;energy&nbsp;minimization.I&nbsp;submit&nbsp;the&nbsp;command&nbsp;"grompp&nbsp;-f&nbsp;minim.mdp&nbsp;-c&nbsp;system_inflated.gro&nbsp;-p&nbsp;topol.top&nbsp;-o&nbsp;em.tpr".The&nbsp;error&nbsp;like&nbsp;this <BR>&nbsp;Back&nbsp;Off!Ijust&nbsp;backed&nbsp;up&nbsp;mdout.mdp&nbsp;to&nbsp;./#mdout.mdp.4# <BR>Generated&nbsp;813&nbsp;of&nbsp;the&nbsp;2346&nbsp;non-bonded&nbsp;parameter&nbsp;combinations <BR>WARING&nbsp;1&nbsp;[file&nbsp;drg.itp,line1]: <BR>Too&nbsp;few&nbsp;parameters&nbsp;on&nbsp;line&nbsp;(source&nbsp;file&nbsp;toppush.c,&nbsp;line&nbsp;1501) <BR><BR>WARING&nbsp;2&nbsp;[file&nbsp;drg.itp,line2]:&nbsp; <BR>Too&nbsp;few&nbsp;parameters&nbsp;on&nbsp;line&nbsp;(source&nbsp;file&nbsp;toppush.c,&nbsp;line&nbsp;1501) <BR><BR>WARING&nbsp;3&nbsp;[file&nbsp;drg.itp,line17]:&nbsp; <BR>Too&nbsp;few&nbsp;parameters&nbsp;on&nbsp;line&nbsp;(source&nbsp;file&nbsp;toppush.c,&nbsp;line&nbsp;1501) <BR><BR>ERROR&nbsp;1&nbsp;[file&nbsp;drg.itp,line&nbsp;21]: <BR>Expected&nbsp;a&nbsp;molecule&nbsp;type&nbsp;name&nbsp;and&nbsp;nrexcl <BR><BR>Program&nbsp;grompp,&nbsp;VERSION&nbsp;4.5.3 <BR>Source&nbsp;code&nbsp;file:toppush.c,&nbsp;line:1187 <BR><BR>Fatal&nbsp;error: <BR>Atomtype&nbsp;\par&nbsp;not&nbsp;found&nbsp;<BR><BR>Is the force&nbsp;field not suitable or others?Thanks!<BR>&nbsp;&nbsp;&nbsp;&nbsp;