[Pw_forum] S matrix not positive definite in Fermi surface calculation

[Paolo Giannozzi]

It's a known problem that occurs with some utrasoft pseudopotentials,
but it doesn't have a simple solution, unfortunately

Paolo
On Wed, 2015-01-21 at 17:28 +0200, Uri Argaman wrote:
> Dear QE users and developers
> 
> I do Fermi surface calculation and I got an error message: 
> "Error in routine cdiaghg (126):
>   S matrix not positive definite"
> 
> I note that in some crystal geometries I got this message and in other
> geometries I didn't got this error and the Fermi surface looks fine
> and reasonable.  
> 
> 
> This is the input file:
> &control
>     calculation='bands'
>     restart_mode='from_scratch',
>     prefix='ti',
>     pseudo_dir='/home/uriargaman/QE/espresso-5.1/pseudo/',
>     outdir='/home/uriargaman/tmp31971/TMP_FS/',
>     tstress = .true. ,
>     tprnfor = .true. ,
>     verbosity='high',
>  /
>  &system
>     ibrav=  4, celldm(1) =5.48090015121, celldm(3) =1.6120416161 ,
> nat= 2, ntyp= 1,
>     ecutwfc =50,ecutrho=500, 
>     occupations='smearing', smearing="methfessel-paxton",
> degauss=0.01,
>      nbnd=16 
>  /
>  &electrons
>     conv_thr =  1.0d-9,
>     electron_maxstep=1000
>     mixing_beta = 0.7d0,
>  /
> 
> ATOMIC_SPECIES
>    Ti   47.9  Ti.bp-sp-van_ak.UPF
> ATOMIC_POSITIONS (crystal)
>    Ti      0.666666666    0.333333333    0.250000000    0  0  0 
>    Ti      0.333333333    0.666666666    0.750000000    
> K_POINTS 
>   4913
> ....
> 
> 
> What can be the problem and how can I solve it?
> 
> 
> Thank you in advance
> 
> Uri Argaman
> 
> Ben-Gurion University
> 
> Israel
> 
> 
> 
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-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222