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Thank you Chris for your answer:<br>
<br>
1) The molecule has no net charge because the virtual site in the
center of mass is a point charge twice the charge in the O atom.<br>
2) Until now I've created 5 files but I don't know if I am doing the
right thing:<br>
<br>
<ul>
<li> forcefield.itp</li>
</ul>
#define _FF_OXY<br>
<br>
[ defaults ]<br>
; nbfunc comb-rule gen-pairs fudgeLJ
fudgeQQ<br>
1 2 no
1.0 1.0<br>
<br>
#include "ffnonbonded.itp"<br>
#include "ffbonded.itp"<br>
<br>
<ul>
<li> ffbonded.itp<br>
</li>
</ul>
[ bondtypes ]<br>
; i j func<br>
O O 5 (I've used function 5 because the forcefield has
a fixed length, is it right?) ;<br>
<br>
<ul>
<li> ffnonbonded.itp</li>
</ul>
[ atomtypes ]<br>
; name at.num mass charge ptype
sigma epsilon<br>
O 8 15.99940 -0.123 A
3.01300e-01 4.0780822e-01<br>
COM 0 0.000000 0.246 V
0.00000e+00 0.0000000e+00<br>
<br>
<ul>
<li> atomtypes.atp<br>
</li>
</ul>
O 15.99940 ; Oxygen Atom<br>
COM 0.0 ; Virtual site (COM charge)<br>
<br>
<ul>
<li> residues.rtp<br>
</li>
</ul>
; Oxygen<br>
[ OXY ]<br>
[ atoms ]<br>
O O -0.123 1<br>
COM COM 0.246 1<br>
[ bonds ]<br>
O O<br>
<br>
3) Is it necessary more or less files? And in which file do I
specificate de virtual site?<br>
4) The virtual site in the COM is [ virtual_sites2 ] with a = 0.5 or
[ virtual_sitesn ]?<br>
<br>
Thank you again for your time.<br>
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