[Wien] c/a ratio optimization

[Duy Le]

For very highly symmetric system, there is no force.

For doing volume optimization, if you have web interface, just follow page
28 in the userguide, there would be no problem.


--------------------------------------------------
Duy Le
PhD Student
Department of Physics
University of Central Florida.


2009/10/6 박지훈 <firstchannel8 at gmail.com>

> Dear Users,
>
>
> Sorry, I did the c/a ratio calculation.
> but I have another question.
>
> I found this on the mailing things.
> >* Date: Wed, 14 Jan 2009 13:40:03 +0530
> *>* From: susanta.phy at gmail.com<http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien>
> *>* To: wien at zeus.theochem.tuwien.ac.at<http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien>
> *>* Subject: Re: [Wien] optimize volume + min_lapw
> *>*
> *>* please do volume optimisation first depending upon your crystal
> *>* structure, i.e. vary volume or c/a or whatever
> *>* you like and then run scf and when it converges you ll find how much
> *>* force in respective atom(s) and then you
> *>* can decide the lattice to relax by running min -I -J "run_lapw -I -fc
> *>* 1.0 -i 40.
> *>*
> *>* so far as i know you can't do both the job simultaneously, so optimise
> *>* volume  and get lattice constants and
> *>* then you can force minimise by relaxing the lattice.
> *
> Is the order of doing this
> 1. StructGen
> 2. initialize calc.
> 3. optimize volume or/and c/a
> 4. run SCF
> 5. relaxation
> ????
>
> The mail above says that I can find how much force in respective atoms???
> I got an error after running "min -I -J "run_lapw -I -fc 1.0 -i 40""
> The error says "Force - convergene not possible. Forces not present."
>
> Do I have to uncomment "runsp_lapw -ec 0.0001" and "min -I -J "run_lapw -I
> -fc 1.0 -i 40"" at the same time?
>
> When I do optimization and relaxation, are the calculated results saved
> automatically?
> What is "#           modify the    save_lapw        command" Do I have to
> use this to save the file? How do I modify this?
>
>
>
>
>
>
>
> All my best,
> Jihoon Park
>
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>
>
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