<table cellspacing="0" cellpadding="0" border="0" ><tr><td valign="top" style="font: inherit;">Hi,<br> I am trying to coarse-grain a system. For that I want to optimize the bond , angle and dihedral parameters of coarse-grained model based on atomistic simulation. For that, in the atomistic simulation part, I want to calculate the the distribution of 'effective' angle made by the 'centre of mass' of the atoms used for coarse-graining ( in stead of using one of the representative atoms used for coarse-graining ). For example, if I have a molecule H3C-CH2-CH3, I want to calculate the angle-distribution of H3C-CH2-CH3 in stead of C-C-C and bond-distribution of H3C-CH2 in stead of C-C .<br>But I do not know how can I invoke the centre of mass of a group of atoms in the index file for g_angle or g_bond.<br>Do I need to create some dummy atoms? If so, how can I do that? <br>Any help will be highly
appreciated.<br>Thanks<br>Jagannath<br><br></td></tr></table><br>
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