[Pw_forum] convergence of SCF calculation of C6H8

[Ruibin Liu]

My qe version is 5.0, and below is the results of last 3 iterations from
the .out file.
 iteration # 48     ecut=    30.00 Ry     beta=0.10
     Davidson diagonalization with overlap
     ethr =  2.88E-04,  avg # of iterations =  3.0

     negative rho (up, down):  0.105E-01 0.000E+00

     total cpu time spent up to now is     1975.6 secs

     total energy              =     -76.44587029 Ry
     Harris-Foulkes estimate   =     -76.46766502 Ry
     estimated scf accuracy    <       0.13146979 Ry

     iteration # 49     ecut=    30.00 Ry     beta=0.10
     Davidson diagonalization with overlap
     ethr =  2.88E-04,  avg # of iterations =  1.0

     negative rho (up, down):  0.105E-01 0.000E+00

     total cpu time spent up to now is     2014.3 secs

     total energy              =     -76.43340310 Ry
     Harris-Foulkes estimate   =     -76.44879474 Ry
     estimated scf accuracy    <       0.08467546 Ry

     iteration # 50     ecut=    30.00 Ry     beta=0.10
     Davidson diagonalization with overlap
     ethr =  2.65E-04,  avg # of iterations =  1.0

     negative rho (up, down):  0.105E-01 0.000E+00

     total cpu time spent up to now is     2052.5 secs

As for other iterations, total energy and estimated accuracy oscillate. Do
you think  what Masoud said is the main problem?

On Mon, Nov 5, 2012 at 3:55 AM, Paolo Giannozzi <giannozz at democritos.it>wrote:

> On Fri, 2012-11-02 at 14:22 -0400, Ruibin Liu wrote:
>
> > I tried to do a scf calculation of C6H8 (CH2CHCHCHCHCH2) with the
> optimized structure [...]  the calculation still cannot converge.
>
> I have tried your data for a smaller cell (25x25x25 a.u.) and it
> converges without any problem
>
> P.
>
> --
> Paolo Giannozzi, IOM-Democritos and University of Udine, Italy
>
>
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-- 
*Liu, Ruibin*
Department of Chemistry
Duke University
Durham, NC, 27708
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