[CPMD-list] question on thermal energy tranfer

[Tengfei Luo]

Dear Axel:

Thank you for your analysis and suggestion. Where can I find the fourier.x 
code? I did some search online, but I couldn't find it anywhere.

Thank you again!

Tengfei

----- Original Message ----- 
From: "Axel Kohlmeyer" <akohlmey at cmm.chem.upenn.edu>
To: "Tengfei Luo" <luotengf at msu.edu>
Cc: <cpmd-list at cpmd.org>
Sent: Saturday, April 07, 2007 2:54 PM
Subject: Re: [CPMD-list] question on thermal energy tranfer


> On Sat, 7 Apr 2007, Tengfei Luo wrote:
>
> TL> Dear All:
>
> TL> I have some question on the result of thermal energy equilibration.
> TL> Experts, could you please look at my inputs to see if there is
> TL> anything wrong?
>
> [...]
>
> TL> But I got a result very strange: the temperature of the two
> TL> materials doesn't go a uniform temperature after the thermostates
> TL> are erased no matter how many steps I run. I cannot explain this
> TL> phenomena physically. Why the temperatures don't go to a same
> TL> temperature, but there is indeed a little temperature drop of high
> TL> temperature side and a little raise in the low temperature side.
>
> have you considered that - due to different atomic masses - bulk
> Si and bulk Ge have different characteristic frequencies and that
> there can be very little overlap of the phonon spectra? even more
> so since are running at very low temperature 50/100K so that only
> low lying phononic states would be excited.
>
> TL> BTW, When I used silicon in both group and germanium in both group,
> TL> the temperature get to a uniform temperature after some thoudands of
> TL> steps. (I wrote a little code to process the trajectory file to
> TL> evaluate the temperature of each part.)
>
> i suggest, you run the velocities from your trajectories (for each
> atom individually and then averaged over groups) through the fourier.x
> code to look at the vibrational spectral densities. bob williams
> has contributed some code to the package for that purpose.
>
> cheers,
>   axel.
>
> TL> I would like to provide any further information if it's needed!
> TL>
> TL> Thank you in advance!
> TL>
> TL> Tengfei
>
> -- 
> =======================================================================
> Axel Kohlmeyer   akohlmey at cmm.chem.upenn.edu   http://www.cmm.upenn.edu
>   Center for Molecular Modeling   --   University of Pennsylvania
> Department of Chemistry, 231 S.34th Street, Philadelphia, PA 19104-6323
> tel: 1-215-898-1582,  fax: 1-215-573-6233,  office-tel: 1-215-898-5425
> =======================================================================
> If you make something idiot-proof, the universe creates a better idiot.
>
>