[gmx-users] potential across surface

Andre Farias de Moura andre at qt.dq.ufscar.br
Thu Aug 5 12:44:16 CEST 2004


hi david,

I forgot to attach the files, here it goes.

andre'

/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/

    Dr. Andre' Farias de Moura

/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/

  Laboratorio de Quimica Teorica
Universidade Federal de Sao Carlos
     Sao Carlos - SP - Brasil

/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/

        Endereco Atual

    Grupo de Quimica Quantica
Instituto de Quimica de Sao Carlos
    Universidade de Sao Paulo
    Sao Carlos - SP - Brasil
    Telefone: 55-16-3373-8055

/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/

---------- Forwarded message ----------
Date: Thu, 5 Aug 2004 10:39:18 +0000 (GMT)
From: Andre Farias de Moura <andre at qt.dq.ufscar.br>
Reply-To: Discussion list for GROMACS users <gmx-users at gromacs.org>
To: Discussion list for GROMACS users <gmx-users at gromacs.org>
Subject: Re: [gmx-users] potential across surface


hi david,

I've checked both and don't think this is the problem,
the density profile shows an interfacial region less
than 0.5 nm thick and there is no overall movement.

my simulation system contains a 6.0 nm water slab in a
50 nm box (z direction), I'm sending you my potential
files to clarify what I mean. I got these files using:

g_potential -f water.xtc -s water.tpr -n index.ndx -sl 50

thanks again,

andre'


/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/

    Dr. Andre' Farias de Moura

/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/

  Laboratorio de Quimica Teorica
Universidade Federal de Sao Carlos
     Sao Carlos - SP - Brasil

/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/

        Endereco Atual

    Grupo de Quimica Quantica
Instituto de Quimica de Sao Carlos
    Universidade de Sao Paulo
    Sao Carlos - SP - Brasil
    Telefone: 55-16-3373-8055

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On Thu, 5 Aug 2004, David van der Spoel wrote:

> On Wed, 4 Aug 2004, Andre Farias de Moura wrote:
>
> >
> >dear gmx-users,
> >
> >I tried to use g_potential to get the potential
> >across air-water interface but I'm not sure
> >about the meaning of potential.xvg output. I
> >expected something like a nearly constant value
> >in bulk water region followed by a steep drop
> >in the interfacial region, but got instead a
> >steadly increasing function with only slight
> >changes across the interface.
> >
> >is that what g_potential should give me?
> >
> >how could I get a potential difference from
> >such plot?
>
> Have you checked how well-defined your interface is (use g_density)?
>
> Is your water slab moving? (remove center of mass motion)
> >
> >thanks in advance,
> >
> >andre'
> >
> >/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/
> >
> >    Dr. Andre' Farias de Moura
> >
> >/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/
> >
> >  Laboratorio de Quimica Teorica
> >Universidade Federal de Sao Carlos
> >     Sao Carlos - SP - Brasil
> >
> >/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/
> >
> >        Endereco Atual
> >
> >    Grupo de Quimica Quantica
> >Instituto de Quimica de Sao Carlos
> >    Universidade de Sao Paulo
> >    Sao Carlos - SP - Brasil
> >    Telefone: 55-16-3373-8055
> >
> >/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/-/
> >
> >_______________________________________________
> >gmx-users mailing list
> >gmx-users at gromacs.org
> >http://www.gromacs.org/mailman/listinfo/gmx-users
> >Please don't post (un)subscribe requests to the list. Use the
> >www interface or send it to gmx-users-request at gromacs.org.
> >
>
> --
> David.
> ________________________________________________________________________
> David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
> Dept. of Cell and Molecular Biology, Uppsala University.
> Husargatan 3, Box 596,  	75124 Uppsala, Sweden
> phone:	46 18 471 4205		fax: 46 18 511 755
> spoel at xray.bmc.uu.se	spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
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-------------- next part --------------
# This file was created by g_potential
# which is part of G R O M A C S:
# GROwing Monsters And Cloning Shrimps
# All this happened at: Thu Aug  5 10:15:44 2004
#
@    title "Electrostatic Potential"
@    xaxis  label "Box (nm)"
@    yaxis  label "Potential (V)"
@TYPE xy
@ view 0.15, 0.15, 0.75, 0.85
@ legend on
@ legend box on
@ legend loctype view
@ legend 0.78, 0.8
@ legend length 2
@ s0 legend "system"
           0               -0
           1         0.467793
           2          1.34466
           3          2.17246
           4          3.02425
           5          4.29521
           6          5.97665
           7          7.24003
           8           8.0797
           9          8.91937
          10          9.75915
          11           10.599
          12          11.4388
          13          12.2784
          14          13.1178
          15          13.9574
          16          14.7971
          17          15.6368
          18          16.4766
          19          17.3161
          20          18.1553
          21          18.9945
          22          19.8339
          23          20.6734
          24          21.5131
          25          22.3528
          26          23.1924
          27          24.0321
          28          24.8718
          29          25.7114
          30          26.5511
          31          27.3908
          32          28.2304
          33          29.0701
          34          29.9098
          35          30.7496
          36          31.5895
          37          32.4293
          38          33.2693
          39          34.1094
          40           34.949
          41          35.7885
          42           36.628
          43          37.4677
          44          38.3075
          45          39.1474
          46           39.987
          47          40.8265
          48          41.6661
          49           42.036
-------------- next part --------------
# This file was created by g_potential
# which is part of G R O M A C S:
# GROwing Monsters And Cloning Shrimps
# All this happened at: Thu Aug  5 10:15:44 2004
#
@    title "Electric Field"
@    xaxis  label "Box (nm)"
@    yaxis  label "Field (V/nm)"
@TYPE xy
@ view 0.15, 0.15, 0.75, 0.85
@ legend on
@ legend box on
@ legend loctype view
@ legend 0.78, 0.8
@ legend length 2
@ s0 legend "system"
           0                0
           1     -9.35586e+08
           2     -8.18139e+08
           3     -8.37478e+08
           4     -8.66096e+08
           5     -1.67581e+09
           6     -1.68708e+09
           7      -8.3967e+08
           8      -8.3967e+08
           9      -8.3967e+08
          10     -8.39891e+08
          11     -8.39891e+08
          12      -8.3967e+08
          13      -8.3945e+08
          14      -8.3945e+08
          15      -8.3967e+08
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          17     -8.39891e+08
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          22      -8.3945e+08
          23      -8.3967e+08
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          31      -8.3967e+08
          32      -8.3967e+08
          33      -8.3967e+08
          34      -8.3967e+08
          35     -8.39891e+08
          36     -8.39891e+08
          37     -8.39891e+08
          38     -8.40111e+08
          39     -8.39891e+08
          40      -8.3945e+08
          41      -8.3945e+08
          42      -8.3967e+08
          43      -8.3967e+08
          44     -8.39891e+08
          45     -8.39891e+08
          46      -8.3945e+08
          47      -8.3945e+08
          48      -8.3967e+08
          49      9.98106e+07
-------------- next part --------------
# This file was created by g_potential
# which is part of G R O M A C S:
# GROwing Monsters And Cloning Shrimps
# All this happened at: Thu Aug  5 10:15:44 2004
#
@    title "Charge Distribution"
@    xaxis  label "Box (nm)"
@    yaxis  label "Charge density (q/nm\S3\N)"
@TYPE xy
@ view 0.15, 0.15, 0.75, 0.85
@ legend on
@ legend box on
@ legend loctype view
@ legend 0.78, 0.8
@ legend length 2
@ s0 legend "system"
           0        -0.109951
           1       0.00654417
           2       0.00643678
           3      -0.00857419
           4       0.00541118
           5       -0.0949061
           6        0.0936608
           7                0
           8                0
           9                0
          10     -2.43636e-05
          11      2.43636e-05
          12                0
          13      2.43636e-05
          14     -2.43636e-05
          15                0
          16                0
          17     -2.43636e-05
          18      4.87271e-05
          19     -3.54191e-12
          20     -3.54191e-12
          21     -3.54191e-12
          22     -2.43636e-05
          23                0
          24                0
          25                0
          26                0
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          28                0
          29                0
          30                0
          31                0
          32                0
          33                0
          34                0
          35     -2.43636e-05
          36      2.43636e-05
          37     -2.43636e-05
          38                0
          39      2.43636e-05
          40      2.43636e-05
          41     -2.43636e-05
          42                0
          43                0
          44     -2.43636e-05
          45      2.43636e-05
          46      2.43636e-05
          47     -2.43636e-05
          48                0
          49         0.103837


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