Hello,
have you put many empty bands in the nscf calculation?
You can only include a limited number of empty bands before running into
troubles: either because the pseudopotentials are not transferable to
such high energies, or because you don't have enough plane-waves to
represent such high energy states.
Otherwise, it may be that your system has a very tiny gap, or no gap at
all at a specific k-point that was not included in the SCF calculation,
but is in the NSCF one.
kind regards
On 08/10/2018 10:25, Ubaid Mohd wrote:
Dear Experts,
I am doing a calculation related to bilayer phosphorene. I have
successfully done vc relaxation and bandstructure calculations. When I
am doing the nscf calculation using the same outdir & prefix flag, I am
getting the error.........
Computing kpt #: 45
total cpu time spent up to now is 4384.4 secs
Computing kpt #: 46
c_bands: 2 eigenvalues not converged
total cpu time spent up to now is 4497.2 secs
Computing kpt #: 47
c_bands: 2 eigenvalues not converged
total cpu time spent up to now is 4611.2 secs
Computing kpt #: 48
c_bands: 4 eigenvalues not converged
total cpu time spent up to now is 4727.0 secs
Computing kpt #: 49
c_bands: 2 eigenvalues not converged
total cpu time spent up to now is 4840.0 secs
Computing kpt #: 50
c_bands: 2 eigenvalues not converged
total cpu time spent up to now is 4946.0 secs
Computing kpt #: 51
c_bands: 2 eigenvalues not converged
total cpu time spent up to now is 5053.2 secs
Computing kpt #: 52
Error in routine cdiaghg (904):
S matrix not positive definite
stopping ...
I search the solution of related problem on google in which error is due
to "atoms are very close to each other" but, if atoms are very close to
each other, why I am getting the optimized structure and the correct
band gap?
How to sort out this problem to proceed the further calcultions like
dos, pdos and charges etc.
Thanks and regards
/Mohammad Ubaid/
/PhD Research Scholar/
/Department of Physics/
/Jamia Millia Islamia University/
/New Delhi - 110025/
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Lorenzo Paulatto - Paris
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