Commit 58c95c97 authored by gsamsonidze's avatar gsamsonidze

Updated documentation on BerkeleyGW interface.

git-svn-id: http://qeforge.qe-forge.org/svn/q-e/trunk/espresso@8770 c92efa57-630b-4861-b058-cf58834340f0
parent 0d07719a
......@@ -11,25 +11,28 @@ input_description -distribution {Quantum Espresso} -package PWscf -program pw2bg
Use "K_POINTS { tpiba | automatic | crystal }" even for the
Gamma-point calculation.
It is recommended to run a pw.x nscf calculation with "K_POINTS crystal"
It is recommended to run a pw.x "nscf" calculation with "K_POINTS crystal"
and a list of k-points produced by kgrid.x, which is a part of BerkeleyGW
package (see BerkeleyGW documentation for details).
Sometimes pw.x adds more k-points when they are specified manually.
Always check if this is the case in the output. If this is the case
then there are several ways to go around this issue:
(1) You can apply the patch provided with BerkeleyGW. This will prevent
pw.x from producing more k-points if they are supplied manually.
(2) Do not supply atomic positions in the input file of kgrid.x (set
number of atoms = 0). Then pw.x will generate additional k-points
which are the correct ones. Do not forget to use noinv = .true. if
time-reversal symmetry is not used in the generation of k-points.
(3) You can do "bands" calculation instead of "nscf" but in this case
you have to explicitly specify occupations in the input file of
pw2bgw.x.
Choose the option that best fits your needs.
You can also run a pw.x "bands" calculation but in this case you have to
explicitly specify the occupations in the input file of pw2bgw.x (note that
this only works for insulators) and to normalize the weights of k-points
to one in the input file of pw.x.
Sometimes pw.x generates additional k-points in a "nscf" run with an explicit
list of k-points. If this is the case for your calculation, there are several
ways to go around this problem:
(1) You can apply the patch provided with BerkeleyGW. It will prevent pw.x
from generating additional k-points if they are provided explicitly,
and take care of the normalization of the weights of k-points in a "bands"
calculation.
(2) Do not specify the atomic positions in the input file of kgrid.x (set
number of atoms = 0). Then pw.x will generate additional k-points which
are the correct ones. Also set noinv = .true. in the input file of pw.x
if time-reversal symmetry was not used in kgrid.x.
(3) You can do "bands" calculation instead of "nscf" (see above).
Structure of the input data:
============================
......@@ -93,7 +96,7 @@ input_description -distribution {Quantum Espresso} -package PWscf -program pw2bg
default { .FALSE. }
info {
overwrite k-grid parameters in BerkeleyGW WFN file.
If pw.x input file contains the manual list of k-points,
If pw.x input file contains an explicit list of k-points,
the k-grid parameters in the output of pw.x will be set to zero.
Since sigma and absorption in BerkeleyGW both need to know the
k-grid dimensions, we patch these parameters into BerkeleyGW WFN file
......
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