Yambo Community Forum

Dear Claudio,
Thank you for your help. When I issued "yambo -b -o b -y d -V resp," no variable denoting the electron-hole energy range appeared with respect to the BS kernel. There were ranges related to Xp and Xs, and changing these did not change the matrix size. I think my Abinit input is very standard and is posted below.

# Crystalline silicon
#
chksymbreak 0
ndtset 2
istwfk2 110*1
symmorphi 0


kptopt 1
ngkpt 4 4 4
nshiftk 4
shiftk 0.5 0.5 0.5
0.5 0.0 0.0
0.0 0.5 0.0
0.0 0.0 0.5

toldfe 1.0d-12

# Print the KSS file
iscf2 -2
getden2 -1
tolwfr2 1.0d-10
nband2 150
nbandkss2 150

#Definition of the unit cell
acell 3*7.2125683
rprim 0.000000 0.707107 0.707107
0.707107 0.000000 0.707107
0.707107 0.707107 0.000000

#Definition of the atom types
ntypat 1
znucl 14

#Definition of the atoms
natom 2
typat 1 1
xred
0.0 0.0 0.0
1/4 1/4 1/4

#Definition of the planewave basis set
ecut 20.0
ecutsm 1.0d-7
nband1 150

#Definition of the SCF procedure
nstep 50
diemac 12.0

I think the solution to my problem may be QP interpolation. I have experimented with this, and increasing the qpoints decreases the binding energy. Is the following the proper way to implement the interpolation?

KfnQPdb= "E < ./SAVE/ndb.QP <iu"

Then I simply change the number of Qpnts from the default to a larger value? This seems to be working. Can you elaborate a bit on how the interpolated values are implemented in the BS calculation? Is there a way to interpolate only near the band edges or must it be done uniformly across the BZ?

EDIT: I am not using sizes for NGsBlkXp and BSENGBlk of 1 either, though this is shown in my old input files. I have not rigorously tested their convergence, but am using values of near 100 for each of these.

Thank you,
Marc

Dear Mark

1) try the Yambo version that is now on subversion (revision 18) where there is the variable BSEEhEny

2) do not confuse QP = quasi-particle with the q-points, the interpolation is for quasi-particles not q-points

3) try to do the calculation with only one grid

nshiftk 1
shiftk 0.0 0.0 0.0

and increase the number of k-points to see if you converge.
You can use the multi-shift grid for the density, this is ok

Claudio