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<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><FONT
size=3><SPAN lang=EN-US><FONT face="Times New Roman">Dear all</FONT></SPAN><SPAN
style="FONT-FAMILY: ·s²Ó©úÅé; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">¡G</SPAN></FONT></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT size=3><FONT face="Times New Roman"><SPAN
style="mso-spacerun: yes"> </SPAN>In order to make sure that
my procedure for applying electric field using Gromacs is correct, I applied
electric fields to sodium chloride solvent (SPC216.pdb with NA+ and CL-) in the
x direction. After 2 ns running, the trajectories of ions and water molecules
showed that both types of ions moved in the same direction, which is obviously
wrong because Na<SUP>+</SUP> and Cl<SUP>-</SUP> are not discriminated by the
electric field. I tried several electric field strengths, ranged from 1 to
0.0001, and the observed phenomena are just the same. </FONT></FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT size=3><FONT face="Times New Roman"><SPAN
style="mso-spacerun: yes"> </SPAN>In order to delineate the
problem, I changed the charge term of NA+ into zero while keeping CL- as -1, in
the ions.itp file, and I found that both ions will then move in the opposite
direction of the NA+=1 CL-= -1 configuration. </FONT></FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><o:p><FONT face="Times New Roman"
size=3> </FONT></o:p></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: justify; mso-char-indent-count: 1.5"><SPAN
lang=EN-US><FONT size=3><FONT face="Times New Roman">In summary, for all the
cases I tried, Na<SUP>+</SUP> and Cl<SUP>-</SUP> moved in the same
direction.<SPAN style="mso-spacerun: yes">
</SPAN></FONT></FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><SPAN style="mso-spacerun: yes"><FONT face="Times New Roman"
size=3></FONT></SPAN></SPAN> </P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT size=3><FONT face="Times New Roman"><SPAN
style="mso-spacerun: yes"> </SPAN>The essential settings for
.mdp file are listed below.</FONT></FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><o:p><FONT face="Times New Roman"
size=3> </FONT></o:p></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT face="Times New Roman" size=3>Comm_mode<SPAN
style="mso-spacerun: yes"> </SPAN>=<SPAN
style="mso-spacerun: yes"> </SPAN>None</FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT face="Times New Roman" size=3>Coulombtype<SPAN
style="mso-spacerun: yes"> </SPAN>=<SPAN
style="mso-spacerun: yes"> </SPAN>PME</FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT face="Times New Roman" size=3>Optimize_fft<SPAN
style="mso-spacerun: yes"> </SPAN>=<SPAN
style="mso-spacerun: yes"> </SPAN>yes</FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT face="Times New Roman" size=3>tcoupl<SPAN
style="mso-spacerun: yes">
</SPAN>=<SPAN style="mso-spacerun: yes">
</SPAN>berendsen</FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT face="Times New Roman" size=3>tc_grps<SPAN
style="mso-spacerun: yes">
</SPAN>= <SPAN style="mso-spacerun: yes"> </SPAN><SPAN
style="mso-spacerun: yes"> </SPAN>SOL<SPAN
style="mso-spacerun: yes"> </SPAN>NA+<SPAN
style="mso-spacerun: yes"> </SPAN>CL-</FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT face="Times New Roman" size=3>tau_t<SPAN
style="mso-spacerun: yes">
</SPAN>=<SPAN style="mso-spacerun: yes"> </SPAN>0.1<SPAN
style="mso-spacerun: yes"> </SPAN>0.1<SPAN
style="mso-spacerun: yes">
</SPAN>0.1</FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT face="Times New Roman" size=3>ref_t<SPAN
style="mso-spacerun: yes">
</SPAN>=<SPAN style="mso-spacerun: yes"> </SPAN>300<SPAN
style="mso-spacerun: yes"> </SPAN>300<SPAN
style="mso-spacerun: yes"> </SPAN>300</FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT face="Times New Roman" size=3>constraints<SPAN
style="mso-spacerun: yes"> </SPAN>=<SPAN
style="mso-spacerun: yes"> </SPAN>none</FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><FONT face="Times New Roman" size=3>E_x<SPAN
style="mso-spacerun: yes">
</SPAN>=<SPAN style="mso-spacerun: yes"> </SPAN><SPAN
style="mso-spacerun: yes"> </SPAN>1<SPAN
style="mso-spacerun: yes"> </SPAN><SPAN
style="mso-spacerun: yes"> </SPAN><SPAN
style="mso-spacerun: yes"> </SPAN>0.1<SPAN
style="mso-spacerun: yes"> </SPAN>2.0</FONT></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><o:p><FONT face="Times New Roman"
size=3> </FONT></o:p></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-ALIGN: justify"><SPAN
lang=EN-US><o:p><FONT face="Times New Roman"
size=3> </FONT></o:p></SPAN></P>
<P class=MsoNormal
style="TEXT-JUSTIFY: inter-ideograph; MARGIN: 0cm 0cm 0pt; TEXT-INDENT: 18pt; TEXT-ALIGN: justify; mso-char-indent-count: 1.5"><FONT
size=3><FONT face="Times New Roman"><SPAN lang=EN-US>Can anyone give me some
clue on this? </SPAN><SPAN lang=EN-US style="mso-font-kerning: 0pt">I¡¦ll
appreciate for any hints on this
question.</SPAN></FONT></FONT></P></FONT></DIV></BODY></HTML>