<HTML><BODY style="word-wrap: break-word; -khtml-nbsp-mode: space; -khtml-line-break: after-white-space; ">Dear Eric.. <DIV>Hi.. </DIV><DIV>This is in regard to your previously replied mail regarding the use of GROMOS96 or OPLS-AA or AMBER force field.</DIV><DIV>As you said it depends upon the users taste which one to use. This means that the three on a broad manner should give convergence of the analyzed data set. </DIV><DIV>Infact from my simulation runs using oplss-aa and gromos96, I didn't found that. I tried using the GROMOS96 and opls-aa force field on my small peptides for a period of 20ns and found that with opls-aa even the phi-psi combination of the individual amino acids were incorrect. Actually this always puzzled me to make a choice for the Force field.  The rest of the script was unchanged for the two runs.</DIV><DIV>Could you please comment on the above results? Is there any way really to judge which force field is to be chosen for particular type of analysis?</DIV><DIV>Best regards</DIV><DIV>Nav</DIV><DIV><BR><DIV> <SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Kai; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Kai; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><SPAN class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px 0px; color: rgb(0, 0, 0); font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; text-align: auto; -khtml-text-decorations-in-effect: none; text-indent: 0px; -apple-text-size-adjust: auto; text-transform: none; orphans: 2; white-space: normal; widows: 2; word-spacing: 0px; "><DIV style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; ">*******************************************</SPAN></DIV><DIV style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; ">Navratna Vajpai</SPAN></SPAN></DIV><DIV style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; ">Ph. D student in Prof. Grzesiek's laboratory</SPAN></SPAN></DIV><DIV style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; ">Department of Structural Biology</SPAN></SPAN></DIV><DIV style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; ">Biozentrum, University of Basel</SPAN></SPAN></DIV><DIV style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; ">Klingelbergstrasse 70,</SPAN></SPAN></DIV><DIV style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; ">CH-4056</SPAN></SPAN></DIV><DIV style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; ">Basel, Switzerland.</SPAN></SPAN></DIV><DIV style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; ">Phone- +41 61 267 2080(O)</SPAN></SPAN></DIV><DIV style="font-family: Helvetica; "><SPAN class="Apple-tab-span" style="white-space:pre; font-family: Helvetica; "><SPAN class="Apple-style-span" style="white-space: pre; ; font-family: Helvetica; "><SPAN class="Apple-style-span" style="white-space: pre; ; font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; white-space: pre; "><SPAN class="Apple-style-span" style="font-family: Helvetica; white-space: pre; ">        </SPAN></SPAN></SPAN></SPAN></SPAN><SPAN class="Apple-style-span" style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; ">       +41 78 744 0810(M)</SPAN></SPAN></DIV><DIV style="font-family: Helvetica; "><BR class="khtml-block-placeholder"></DIV><DIV style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; "><SPAN class="Apple-style-span" style="font-family: Helvetica; "><A href="mailto:navratna.vajpai@unibas.ch">navratna.vajpai@unibas.ch</A></SPAN></SPAN></DIV><DIV style="font-family: Helvetica; "><BR class="khtml-block-placeholder"></DIV><BR class="Apple-interchange-newline"></SPAN></SPAN></SPAN></SPAN> </DIV><BR></DIV></BODY></HTML>