
From:  Georg Rempfer 
Subject:  Re: [ESPResSousers] Mass scale in simulations 
Date:  Thu, 23 May 2019 21:14:56 +0200 
I think I might be the last one to touch that part of the documentation. I meant to say exactly what Ricky took from it: The time scale does depend on the mass of an individual particle, and not the combined mass of all particles. The time scale therefore is independent of the number of particles. Sorry for the confusion.Dear David,In my opinion, if you don't activate the "MASS" feature, then all the particles have the same reduced mass of 1. And the resulting time scale is[time] = [length] \sqrt{ [mass] / [energy] } as the document said.So the time scale is independent of the number of particles.Regards!Ricky
From: GeiseldDate: 20190522 18:10To: espressomdusersSubject: [ESPResSousers] Mass scale in simulationsDear all,I have a question concerning the mass scale of the simulations in espresso.The documentation states that"By default, ESPResSo uses a reduced mass of 1,so that the mass unit is simply the mass of all particles."How is this statement to be interpreted? Does the time scale of mysimulations changewhen I add particles to the simulation, like[time] = [length] \sqrt{ #particles* [mass] / [energy] }or do I still only use the mass of one particle and assume that allparticles have the same mass?To test this I constructed a simple simulation of diffusing particlesand calculated thediffusion coefficient of a single particle (which should beindependent of the number ofparticles in the box (no interactions)).Here, it seemed as if the time scale was independent of the number ofparticles. Is this correct?I would be very thankful for advise,best regards,David.
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