[ESPResSo-users] Control Temperature in version 3.2

[Salvador H-V]

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