Indeed, if you do the other way:<div><br></div><div> 0.65084/4.184 = 0.15555 ~ 0.156</div><div><br></div><div>Alan<br><br><div class="gmail_quote">On 6 October 2011 08:17, Yun Shi <span dir="ltr"><<a href="mailto:yunshi09@gmail.com">yunshi09@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">Hi Alan,<br><br>So is acpype using a conversion factor of 4.184 for dihedral force constant?<br><br>I found some dihedral constants as 0.156 in the amber format, which should be 0.156*4.184=0.652704 in gromacs unit. However, acpype gave a force constant of 0.65084 after conversion, which is slightly off. I wonder if this is OK, and I suspect it might be that I used rdparm to check the amber format value, which only gives 3 decimals for force constants.<br>
<br>Thanks for the reply,<br>Yun<br><br><br>>Hi Yun,<br>
><br>
>ACPYPE is working fine. What happens here is I choose the >reproduce the<br>
>exact values one sees in AMBER.<br>
><br>
>Now why GMX tip3p file choose a different value, I don't know.<br>
><br>
>Nevertheless, it's pretty simple to put whatever value you want there >if you<br>
>think you need.<br>
><br>
>Alan
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