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[ESPResSo-users] Regarding Standard DPD vs Transverse DPD
From: |
Salvador H-V |
Subject: |
[ESPResSo-users] Regarding Standard DPD vs Transverse DPD |
Date: |
Sat, 10 Mar 2012 17:06:05 -0600 |
Hi ESPResSo Users,
I am perfuming some simulations using DPD in ESPReSo to reproduce the coefficient diffusions reported in: Soft Matter 2008,4,156.
In particular i am trying to reproduce the diffusion coefficient of 4000 LJ repulsive (WCA) particles in 3D (figure1).
I create a script with the specified conditions and parameters by the authors. Then I compiled ESPResSo twice, one with DPD feature activated and another with only Trans_DPD.
Here it is the code info for each compilation:
a) Just DPD feature
ESPResSo: 3.0.2
{ Compilation status { FFTW } { MODES } { PARTIAL_PERIODIC } { ELECTROSTATICS } { MASS } { EXTERNAL_FORCES } { CONSTRAINTS } { BOND_CONSTRAINT } { EXCLUSIONS } { TABULATED } { LENNARD_JONES } { SOFT_SPHERE } { LJCOS } { LJCOS2 } { BOND_ANGLE_HARMONIC } { NPT } { DPD } }
{ Debug status { MPI_CORE FORCE_CORE } }
b) Trans_DPD
ESPResSo: 3.0.2
{ Compilation status { FFTW } { MODES } { PARTIAL_PERIODIC } { ELECTROSTATICS } { MASS } { EXTERNAL_FORCES } { CONSTRAINTS } { BOND_CONSTRAINT } { EXCLUSIONS } { TABULATED } { LENNARD_JONES } { SOFT_SPHERE } { LJCOS } { LJCOS2 } { BOND_ANGLE_HARMONIC } { NPT } { TRANS_DPD } { DPD } }
{ Debug status { MPI_CORE FORCE_CORE } }
To run the simulations I am using for both kind of simulations (thermostats) the following commands:
thermosat off
galileiTransformParticles
set temp_ave 1.2
set gamma_dpd 1.0
set dpd_cut [ expr { ( pow ( 2.0 , 1.0/6.0 ) )*$diam } ]
thermostat dpd $temp_ave $gamma_dpd $dpd_cut WF 1
to obtain the different diffusion coefficients I have changed gamma_dpd accordingly to {0.5,1.0,2.0,3.0,5.0,7.0 & 10.0}
For the kinetic temperature and pressure I am obtaining similar values as those reported in the article for both thermostats.
Using the standard DPD thermostat I am able to obtain a similar behavior of Dt as the authors shown in figure1. However, even when I am using the same script and running the simulation with the correspondingly ESPResSo compilation I can not reproduce the results for the coefficient diffusion using the Transverse-DPD thermostat. I mean, I can not observe the drastically reduction in the coefficient diffusion as gamma_dpd increases form 0.5 to 10.
Anny comment or suggestion of possible causes of errors or mistakes in my procedure would be greatly appreciated.
Thanks a lot,
Salvador
- [ESPResSo-users] Regarding Standard DPD vs Transverse DPD,
Salvador H-V <=