The ABINIT Users Mailing List ( CLOSED )

[matthieu verstraete <matthieu.jean.verstraete@gmail.com>]

Hello abinists,

I have come upon a strange behavior in abinit (not the first, of course) and was wondering if anyone had heard of it or an explanation (v5.6 on opteron 64 bit RHEL, g95 compiled, sequential).

In converging a ground state for graphene (what else), I need to use only symmorphic symmetry operations. The strange behavior is that, without the non-symmorphic symmetry operations, abinit does not converge the wavefunctions below 1.e-13 or so (even after 200 steps), and the eigenvalues are not converged below mHa accuracy. With all the symops the convergence down to tolwfr 1.e-20 is effortless. Why the difference? Numerical noise is one possibility, but plenty of symops are left in the calculation...

Matthieu

-- 
input file

# etsfio
prtvxc 1
prtden 1
accesswff 3
istwfk 127*1

acell 2*2.46 10. Angstr
angdeg 90 90 120

#symmorphi 0

znucl 6
natom 2
ntypat 1
typat 1 1
xred
0 0 0.
1./3. 2./3. 0.

ecut  35

kptopt 1
nshiftk 1
shiftk  0 0 0
ngkpt 36 36 1
tsmear 0.1 eV
#tsmear 0.0001
nband 10
nbdbuf 2
tolwfr 1.0e-20
nstep 200



~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr. Matthieu Verstraete

European Theoretical Spectroscopy Facility (ETSF) 
Dpto. Fisica de Materiales, 
U. del Pais Vasco,            
Centro Joxe Mari Korta, Av. de Tolosa, 72,   Phone: +34-943018393
E-20018 Donostia-San Sebastian, Spain        Fax  : +34-943018390

Mail : matthieu.jean.verstraete@gmail.com
http://www-users.york.ac.uk/~mjv500