[gmx-users] LJ Switch function in the CVS VERSION 3.3_beta_20050202
lindahl at sbc.su.se
Fri Sep 9 11:01:50 CEST 2005
David is right - the switching function was changed to 5th order to
make both potential and force smooth. However, I too recommend
against using switched interactions due to the artificial _increase_
in force when switching.
On Sep 9, 2005, at 8:19 AM, David wrote:
> On Thu, 2005-09-08 at 18:35 -0400, Xuhui Huang wrote:
>> Dear Gromacs users,
>> We noticed that the LJ switch function in the CVS Version
>> 3.3_beta_20050202 gives the wrong energy. We tested this with the
>> water system in the tutor. With the LJ switch function, the CVS
>> version gives the LJ(SR) energy of 9.28495e+02 kJ/mol, however, the
>> Gromacs 3.1.4 gives the energy of 2.00385e+03 kJ/mol. With the LJ
>> off, both version gives the energy about 2.0e+03 kJ/mol.
>> Does anyone notice this problem before?
> Somehow I recall that the functional for for switch changed. Since
> it is
> useless anyway (except for maybe an Argon system), don't wast any time
> on it.
>> The following is our parameters about the LJ switch part in
>> the .mdp part,
>> ; Method for doing Van der Waals
>> vdw-type = Switch ;Cut-off
>> ; cut-off lengths
>> rvdw-switch = 0.75
>> rvdw = 0.85
>> gmx-users mailing list
>> gmx-users at gromacs.org
>> 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 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/
> gmx-users mailing list
> gmx-users at gromacs.org
> Please don't post (un)subscribe requests to the list. Use the
> www interface or send it to gmx-users-request at gromacs.org.
More information about the gromacs.org_gmx-users