[Wien] Calculations at moderate T

[Dr. Sharat Chandra]

If the bulk thermal expansion is anisotropic it would also mean that we 
will have to take the appropriate values. In the case of a surface it 
might be anisotropic even if that for the bulk material is isotropic.

On Tue, 9 Apr 2013, Laurence Marks wrote:

> Date: Tue, 9 Apr 2013 18:50:16 -0500
> From: Laurence Marks <L-marks at northwestern.edu>
> Reply-To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
> To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
> Subject: Re: [Wien] Calculations at moderate T
> 
> Thanks. Method a) is the only reasonable one, coupled with
> extrapolating the bulk reference lattice parameters. This would have
> to be done by a uniform volume expansion without relaxation of course.
>
> On Tue, Apr 9, 2013 at 3:03 PM, Peter Blaha
> <pblaha at theochem.tuwien.ac.at> wrote:
>> a) Simply empirically extrapolate a0 to a possible value at 1200 K.
>>
>> b) Ab initio: quasiharmonic approximation.
>>     Calculate phonons (wien2k + ponon or phonopy, see u supported sw)
>>     and resulting -TS at various lattice parameters and
>>     search for the minimum of the free energy as function of a0
>>     at the desired T
>>
>> Of course, for a surface this is more difficult. Of course one can use the
>> expanded a,b lattice constants, but relaxation of z will still corrsepond
>> to t=0. It is more a simulation of an epitactically expanded lattice.
>>
>> Am 09.04.2013 19:38, schrieb Laurence Marks:
>>> Does anyone know of methods to do calculations at T~1200K taking
>>> account of bulk thermal expansion? I am interested in a surface
>>> calculation where I suspect that it may be important to consider this,
>>> and a moderately rational approach to doing this that has been
>>> tested/published would be useful.
>>>
>>
>> --
>> -----------------------------------------
>> Peter Blaha
>> Inst. Materials Chemistry, TU Vienna
>> Getreidemarkt 9, A-1060 Vienna, Austria
>> Tel: +43-1-5880115671
>> Fax: +43-1-5880115698
>> email: pblaha at theochem.tuwien.ac.at
>> -----------------------------------------
>> _______________________________________________
>> Wien mailing list
>> Wien at zeus.theochem.tuwien.ac.at
>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>> SEARCH the MAILING-LIST at:  http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>
>
>
>

-- 
Dr. Sharat Chandra %%%%%%%%%%%_%%%%%%%%%%%%%%___%%%%%%% Home Address %%%%%%%
Scientist & Asst. Prof. HBNI (_) ___   ___  / _ \  ___  117, Fifth Avenue
Materials Science Group,     | |/ _ \ / __\| |_| |' _ \ DAE Township
IGCAR, Kalpakkam,            | | (_) | |__,|  _  | | \| Kalpakkam
603102, Tamil Nadu, INDIA    |_|\__/ |\___/|_| |_|_|    603102 TN INDIA
Ph: +91 44 27480500*22167  %%%% / /| | %%%%%%%%%%%%%%%% +91 44 27481521
email: sharat at igcar.gov.in %%%%| |_| | %%%%%%%%%%%%%%%% sharat.c at gmail.com
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%\___/%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%