[Wien] lapw2c run-time error (with suggested code correction)

[Michal Wierzbicki]

lapw2c crashed during an SCF calculation of BaC crystal in the wurtzite
structure with an 'illegal instruction' message. I am using the followig 
software:

Wien2k 08.1
Intel Fortran 9.1.052
Intel MKL 9.0

I recompiled SRC_lapw2/* with the following compiler options

FOPT =  -FR -mp1 -w -prec_div -pc80 -O0 -traceback -check -debug

Then I got the following error message:

forrtl: severe (408): fort: (2): Subscript #1 of the array EB has value 63
which is greater than the upper bound of 62
Image              PC        Routine            Line        Source
lapw2c             08127BAE  eweigh_                   648  fermi_tmp_.F

It seems that error is at line 648 in fermi.F file. There is a logical .and.
in the do-while loop condition there.
If the first condition "(nn+ndeg).le.nnn" is false optimizing compiler
may decide to not evaluate the rest.
However if it does then the second condition requires the element
eb(nn+ndeg,kk,jspin1) of an array which is out of bound.
I think the solution is to split the logical .and. and evaluate the rest
inside the do-loop, with the conditional exit out of the loop.

******************* patch begins *****************************************

--- fermi.F.orig        2008-02-09 23:07:58.000000000 +0100
+++ fermi.F     2008-02-09 23:34:17.000000000 +0100
@@ -644,8 +645,8 @@
          wecp=weight(nn+(jspin1-1)*nnn,kk)
  !
  ! check degeneracy
-        do while((nn+ndeg).le.nnn.and. &
-                 abs(eb(nn+ndeg,kk,jspin1)-eb(nn,kk,jspin1)).lt.abs(cordeg))
+        do while((nn+ndeg).le.nnn)
+         if(abs(eb(nn+ndeg,kk,jspin1)-eb(nn,kk,jspin1)).lt.abs(cordeg)) exit
            if(abs(weight(nn+ndeg+(jspin1-1)*nnn,kk)     &
                  -weight(nn+(jspin1-1)*nnn,kk)).ge.1e-6) ifcp=1
            wecp=wecp+weight((nn+ndeg)+(jspin1-1)*nnn,kk)

******************** patch ends ******************************************
With regards,

Michal Wierzbicki
Faculty of Physics
Warsaw University of Technology
Koszykowa 75 00-662 Warszawa
Poland