The ABINIT Users Mailing List ( CLOSED )

["Artem R. Oganov" <a.oganov@mat.ethz.ch>]

Dear Rongqin,

 

As the Nose thermostat describes coupling of your system to an external heat bath, the period of temperature oscillations should be close to the most typical vibrational period in your solid – otherwise coupling will not be effective. As to the rms fluctuation, it will decrease as the system size is increased – as you know very well.

 

With my best regards,

Artem

++++++ESF/CECAM/Psi-k Workshop: http://www.wrc.man.ac.uk/cecam/

************************
Dr. Artem R. Oganov
Lab. of Crystallography, Department of Materials
ETH Zurich, CH-8092 Zurich, Switzerland
Tel.: +41-1-632-3752; Fax: +41-1-632-1133
E-mail: a.oganov@mat.ethz.ch
Personal web-page: http://olivine.ethz.ch/~artem
Group page:  http://www.crystal.mat.ethz.ch/research/ExtremeConditions
************************

-----Original Message-----
From: Wu Rongqin [mailto:g0203654@nus.edu.sg]
Sent: 25 May 2004 06:50
To: forum@abinit.org
Subject: [abinit-forum] molecular dynamics

 

Dear all,

I use abinit to do molecular dynamics on a liquid system with 64 atoms at 1000k. after long time run, 15ps the temperature is still fluctuating, it should fluctuate as the system has finite degrees of freedom. But for such a system, what a fluctuating is acceptable? In my case, the maximum fluctuation is 150k. I use a nose thermostat.

As I use different nose thermostat frequency, the temperature fluctuation behavior is quite different. What is the difference between different nose frequencies?

I attach two temperature fluctuation with time, which one is better?

Regards

Rongqin