<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=Content-Type content="text/html; charset=windows-1255">
<META content="MSHTML 6.00.6000.16825" name=GENERATOR>
<STYLE></STYLE>
</HEAD>
<BODY bgColor=#ffffff>
<DIV><FONT face=Arial size=2>I've been using the EXX routine to calculate
electronic structure. The routine can calculate the orbital energies at the
k-points used in the scf calculation. In an effort to calculate the electronic
structure for a general k-point I have been adding the general k-point with an
infinitesimal weight to the list of k-points used in the scf calculation along
with its symmetry points e.g for nq=4,4,1 </FONT></DIV>
<DIV><FONT face=Arial size=2>K_POINTS<BR> 18<BR>
0.0000000 0.0000000 0.0000000 0.03125<BR>
-0.2500000 0.2500000 -0.2500000 0.25000<BR>
0.5000000 -0.5000000 0.5000000 0.12500<BR>
0.0000000 0.5000000 0.0000000 0.18750<BR>
0.7500000 -0.2500000 0.7500000 0.75000<BR>
0.5000000 0.0000000 0.5000000 0.37500<BR>
0.0000000 -1.0000000 0.0000000 0.09375<BR> -0.5000000
-1.0000000 0.0000000 0.18750<BR>
0.0000000 0.0000000 0.001000 0.0000001<BR>
0.2500000 0.2500000 0.25100 0.0000001<BR>
0.5000000 0.5000000 0.501000 0.0000001<BR>
0.7500000 0.7500000 0.751000 0.0000001<BR>
0.0000000 0.0000000 0.501000 0.0000001<BR>
0.2500000 0.2500000 0.751000 0.0000001<BR>
0.5000000 0.5000000 1.001000 0.0000001<BR>
0.0000000 0.0000000 1.001000 0.0000001<BR>
0.25
0.25 1.251
0.0000001<BR> 0.0
0.0
1.501 0.0000001</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>This method works fine for LDA routines. It also
works OK with the functional we made (BNL, which is a type of hybrid functional
of LDA and explicit exchange) when the weight given to the explicit exchange is
small. However when I use only the explicit exchange routine or the EXX routine
has a more significant weight than LDA, I get spurious results for the general
k-point.</FONT></DIV>
<DIV><FONT face=Arial size=2>For example when q=4,4,1 for bulk Si</FONT></DIV>
<DIV><FONT face=Arial size=2>I get at k=0,0,0 orbital energies 3.3785eV
and 11.6304eV</FONT></DIV>
<DIV><FONT face=Arial size=2>but at k=0,0,0.001 orbital energies 2.7821eV and
11.8583eV</FONT></DIV>
<DIV><FONT face=Arial size=2>when the energies at k=0,0,0.001 should be almost
the same as those at k=0,0,0</FONT></DIV>
<DIV><FONT face=Arial size=2>This problem doesn't occur when q=1,1,1 and occurs
to a lesser extent when q=2,2,1. The results for the 'normal' k-points are fine
the problem is only with the general k-point.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Can anybody (especially Dr. de Gironcoli)<FONT
size=3> </FONT>explain this problem?</FONT></DIV>
<DIV><FONT face=Arial size=2>Thank you for your help,</FONT></DIV>
<DIV><FONT face=Arial size=2>Dr. Helen Eisenberg,</FONT></DIV>
<DIV><FONT face=Arial size=2>Fritz-Haber Center for Molecular
Dynamics,</FONT></DIV>
<DIV><FONT face=Arial size=2>Hebrew University</FONT></DIV></BODY></HTML>