Dear Singaravelan
nscf or band calculations must be strictly performed *after* scf
calculations, using the very same scf potential and calculating with
this potential the eigenvalues at whatever k-point, requiring less
computational resources than scf calculations. Intrinsically, there is
no strict convergence criterion. Of course it would be pointless to
perform a nscf calculation with less or the very same k-points of the
scf calculation, but the exact number of nscf k-points actually used
depend on the purpose of the nscf calculation (eg, band structure, stm
imaging, calculation of DOS, input of a following GW calculation,
transport calculation, ...). In this regard, you should verify the
desired convergence of the property you are interested in with respect
to the k-points.
HTH
Giuseppe
singaravelan T R <[email protected]> ha scritto:
Dear all,
Let I am performing calculation for silicon.
I performed convergence test for no.of k points with the scf calculation
and found that no. of k points as 4 4 4 0 0 0.
*Question:For nscf calculation the no. of k points has to be doubled or not
?. That is: 8 8 8 0 0 0.*
For nscf calculation too, if we need to optimize the no. of k points , then
there is no point in optimization of k points for scf calculation. We can
straight away optimize the k points in nscf calculation itself.
Because to my knowledge all the convergence and optimization has to be
performed with self consistent field (scf) calculation. After optimization
only we do nscf calculation.
With thanks,
Singaravelan T R
GIUSEPPE MATTIOLI
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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I-00015 - Monterotondo Scalo (RM)
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E-mail: <[email protected]>
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