[Wien] optimization

[Peter Blaha]

Yes, but you would NEVER do the whole optimization with this large parameter,
only at the very end you switch to it.

Santhy Jaiker schrieb:
> Dear Blaha,
> Thanks for your reply. 
> I want to find the enthalpy of formation of Fe2Ti.  I know that RKMAX=10 
> is high for Fe2Ti.  I thought that higher RKMAX will increase the 
> accuracy and computation time.   I have chosen convergence criteria for 
> RKAMX is <5mev/atom (~0.0003Ry/atom).    For Fe in BCC and Ti in HCP, 
> satisfies this condition when RKMAX is 10.  So highest RKMAX should be 
> used to find out the energy of the elements and compound.   That’s why I 
> used RKMAX=10. 
> Am I correct?
> 
> 
> */Peter Blaha <pblaha at theochem.tuwien.ac.at>/* wrote:
> 
>     Certainly the message:
>     mini.error (stop in mini forces small)
>     is NOT an error, but leads to a stop because the optimization has
>     finished properly.
> 
>     The
>     lapw1.error (Cholesky INFO = 2198 'SECLR4' - POTRF
>     (scalarpack/lapack) failed)
>     is a "real" error. Often it comes because your structure is wrong
>     (sometimes the
>     optimization may break symmetry (move atoms in a symmetry breaking
>     way!).
> 
>     Otherwise, your RKMAX=10 may be too large.
>     Why would you do it that way ?
> 
>     Start with the default (RKMAX=7). It is probably 100 times !!!! faster.
>     Anc once you have the minimum with RKMAX=7; you continue with
>     RKMAX=8 and
>     check if the minimum has changed. If not, you are done.
> 
>     Santhy Jaiker schrieb:
>      > I am trying to optimize Fe2Ti system for more than a month. Still
>     i am
>      > facing problem in it.
>      >
>      > Structure Details: Positions of atoms Fe (0,0,0) and
>     (0.1705,0.341,1/4)
>      > Ti (1/3,2/3,0.5647)
>      > a=b=4.794 A c=7.834 A
>      > alpha=beta=90 degree gamma=120 degree
>      > Parameters: RMT (of Fe and Ti) =2 k point =76 IBZ Gmax=14
>      > mixer=0.20 RKmax=10
>      >
>      > Force are there in atom 2 and atom 3
>      >
>      > SCF and mini calculation runs nicely.
>      > During optimization with mini, varying volume from -5 to 0%, it
>      > shows error in
>      > -3% volume reduction. It shows mini.error (stop in mini forces small)
>      >
>      > Since i tried optimization without mini, it runs nicely from -5
>     to 0%
>      > volume reduction. But it shows error in c/a ratio optimization. Both
>      > mini.error (stop in mini forces small) and lapw1.error (Cholesky
>     INFO =
>      > 2198 'SECLR4' - POTRF (scalarpack/lapack) failed).
>      >
>      > I know that i am doing mistake some where. Because of that i
>     tried all
>      > the possiblities. But i am not able to trace it out. Any suggestions
>      > regarding this problem will be helpful.
>      >
>      > Thanks in advance
>      >
>      >
>      > Regards,
>      > Santhy Jaiker
>      >
>      > Research Scholar,
>      > Materials Thermodynamics Lab,
>      > Department of Metallurgical and Materials Engineering,
>      > Indian Institute of Technology Madras,
>      > Chennai - 600 036, India
>      > Tel: 91-044-22575763
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>     -- 
> 
>     P.Blaha
>     --------------------------------------------------------------------------
>     Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
>     Phone: +43-1-58801-15671 FAX: +43-1-58801-15698
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> 
> 
> 
> Regards,
> Santhy Jaiker
>  
> Research Scholar,
> Materials Thermodynamics Lab,
> Department of Metallurgical and Materials Engineering,
> Indian Institute of Technology Madras,
> Chennai - 600 036,  India
> Tel: 91-044-22575763
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> A truly happy person is one
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                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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