Re: [ESPResSo-users] Control Temperature in version 3.2

[Olaf Lenz]

Hi!

Could you try whether this also happens when you turn off
ROTATION_PER_PARTICLE?

In general, when you just do a standard simulation, DO NOT turn on
ROTATION, as this will make ESPResSo significantly slower.

Anyway, this is a problem that should be solved.

Olaf

On 05/13/2013 08:43 PM, Salvador H-V wrote:
> Dear All,
> 
> I have a one-dimensional system of spherical particles of diameter
> sigma move along a line.
> 
> I am using #   --- The simulation Box is periodic in only one
> direction setmd periodic 1 0 0 setmd box_l $bl $bl $bl and the
> interaction potential is either the WCA, hertzian or Gaussian 
> potential
> 
> My compilation of ESPresSo is as follows: ESPResSo-3.2.0 {
> Compilation status { FFTW } { CONSTRAINTS } { ROTATIONAL_INERTIA } { 
> BOND_ANGLE_HARMONIC } { GAY_BERNE } { GAUSSIAN } { COMFIXED } {
> HERTZIAN } { PARTIAL_PERIODIC } { LENNARD_JONES } {
> VIRTUAL_SITES_RELATIVE } { EXTERNAL_FORCES } { TABULATED } { ROTATION
> } { SOFT_SPHERE } { VIRTUAL_SITES_NO_VELOCITY } {
> LENNARD_JONES_GENERIC } { ROTATION_PER_PARTICLE } { BOND_VIRTUAL } }
> 
> I am running the simulation with: { langevin 1.0 1.0 }
> 
> However, with the current version of ESPresSo 3.2.0, I have problems
> to control the temperature with any of the above mentioned
> potentials.
> 
> WCA-Potencial {0 0 lennard-jones 1.0 0.5 0.5612310241546865 0.25 0.0
> 0.0 0.0 } t=1.000000000000001 E=1.784989386884216, T=3.5299316707096
> (LJ cap = 20) t=2.000000000000001 E=2.105429430274374,
> T=4.149024028202554 (LJ cap = 30)
> 
> However, for the same script with the same set of parameters using 
> version 3.1.1, I get the following {0 0 lennard-jones 1.0 0.5
> 0.5612310241546865 0.25 0.0 0.0 0.0 } { langevin 1.0 1.0 }
> 
> t=1.000000000000001 E=0.4317609210550725, T=0.8207101850023056 (LJ
> cap = 20) t=2.000000000000001 E=0.5662738721667048,
> T=1.071506110193384 (LJ cap = 30)
> 
> I observe the same problem with both WCA and Hertzian potentials. 
> Correct temperature in 3.1.1 but not in 3.2.0
> 
> Does any body could shed some light?  Any suggestion would be
> greatly appreciated.
> 
> Thanks a lot in advance,
> 
> Salvador
> 
> 
> 


-- 
Dr. rer. nat. Olaf Lenz
Institut für Computerphysik, Allmandring 3, D-70569 Stuttgart
Phone: +49-711-685-63607

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