<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman, new york, times, serif;font-size:12pt;color:#000000;"><DIV>Hello,</DIV>
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<DIV> I am currently running MD on a protein-ligand complex centered in an (approx) 70.0 Angstrom ^3 water box with sodium counterions. I have run 1.0 ns simulations under two different conditions. The first condition with coulombtype "cut-off" I have run to perform LIE calcs as I have read PME will cause undesired artifacts. These runs tend to be unstable though with only varying success on obtaining completed production runs before box collapses. However, when I run under condition 2 (PME) I find that there is no problem at all, though I cannot then run g_lie (obviously). Would creating a bigger solvent box help in making the use of cut-offs more stable? Is there not a preferred ratio of rcoulomb distance to some solvent box dimension that might alleviate this issue? Otherwise, what is it about PME exactly that creates issues for g_lie? Is there a way around it? Any guidance would be appreciated.</DIV>
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<DIV>Regards, Marc</DIV>
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<DIV><STRONG>Condition 1</STRONG></DIV>
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<DIV><SPAN lang=EN>
<P>ns_type = grid</P>
<P>pbc = xyz</P>
<P>rlist = 0.9</P>
<P>coulombtype = cut-off</P>
<P>rcoulomb = 1.2</P>
<P>vdwtype = cut-off</P>
<P>rvdw = 1.4</P>
<P> </P>
<P><STRONG>Condition 2</STRONG></P>
<P> </P><SPAN lang=EN>
<P>ns_type = grid</P>
<P>rlist = 0.9</P>
<P>coulombtype = PME</P>
<P>rcoulomb = 0.9</P>
<P>vdwtype = cut-off</P>
<P>rvdw = 1.4</P>
<P>fourierspacing = 0.12</P>
<P>fourier_nx = 0</P>
<P>fourier_ny = 0</P>
<P>fourier_nz = 0</P>
<P>pme_order = 6</P>
<P>ewald_rtol = 1e-5</P>
<P>optimize_fft = yes</P></SPAN></SPAN></DIV></div></body></html>