<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:garamond, 'new york', times, serif;font-size:12pt;color:#000000;">Dear all, <div><br></div><div>I tried to include 2 tabulated dihedral potential functions into my simulation. But it seems to be not able to generate correct results. The system just exploded. I defined 3601 points in each table (from -180 to 180 with an increment 0.1). After 'mdrun', GOMACS generates two warning information:</div><div><br></div><div>WARNING: For the 3598 non-zero entries for table 0 in table_d1.xvg the forces deviate on average 193% from minus the numerical derivative of the potential</div><div>WARNING: For the 3598 non-zero entries for table 0 in table_d2.xvg the forces deviate on average 193% from minus the numerical derivative of the potential<br><div> </div><div>Do these two warnings matter very much? I checked the values for x,f(x),-f'(x) in the tables and
don't think there're mistakes. has anyone of you met with such problems? </div><div><br></div><div>There're also some other confusions:</div><div>1. Can the constant k before the cubic spline function be defined arbitrarily, as long as the multiplication of k and f(x) equals to the dihedral potential? </div><div>2. The tables do not need to be supplied to mdrun using '-tableb', right? I found if I omitted -tableb and the following table files, GROMACS can still go and find the two tables. </div><div>3. how to use '-tableb' if two tables are supplied? '-tableb table_d1.xvg table_d2.xvg' or '-tableb table_d1.xvg -tableb table_d2.xvg'? I tried both and error information was given that GROMACS can not find 'table_d1_d1.xvg'. I then delete '_d1' in both of the commands and there was no error information any more. It seems that only one table can be supplied to mdrun by using'-tableb', the second table can not be recognized all the
time.</div><div><br></div><div>Thanks for your help</div><div>CH</div><div style="position:fixed"></div></div></div><br>
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