To Whom It May Concern,

        We have recently begun geometry optimization calculations on
different CO-systems (with several CO--CO complexes and so forth).
For one peculiar input geometry (with only 4 atoms), ADF terminates
before staring the geom. opt. with an error message in the output
file:
NO INDEPENDENT BASIS. PNTGRP

We find this really odd since the same input file with other input
coordinates gives a "normal termination" output file.

Given below is the actual input file. But before going straight to
it, two notes should be mentioned.

Note 1:
The reason for non-zero coordinates is that we want a 3D molecule
in our calculation (since we have seen that for some systems,
if the input structure does not lie in a plane (or on a line), the
resulting total bondning energy of the system is lower than if the
input structure would have been two- or one-dimensional).
In other words, the input structure given below is only "almost"
linear.

Note 2:
In this input file, we create the C and O atoms only once. We have
also tried creating as many atomic bases as there are atoms in the
system, labelling the atoms C.1, C.2, O.1 and O.2 for a 2CO system
such as this one (and ofcourse labelling the fragments accordingly).
But none of this has helped.

So then, here is the input file:

#! /bin/sh
PROG=$ADFBIN/adf

$PROG <<eor
  create C $ADFRESOURCES/IV/C.1s
xc
lda vwn
end
endinput
eor

mv TAPE21 t21.C
rm [A-Z]* logfile

$PROG <<eor
create O $ADFRESOURCES/IV/O.1s
xc
lda vwn
end
endinput
eor

mv TAPE21 t21.O
rm [A-Z]* logfile

$PROG << eor
title COCO from atoms

units
length angstrom
end

PRINT Atdist

atoms
1. C 0.0 0.0 0.0
2. O 1.131212 0.0 0.0
3. C 2.5 -0.02 0.02
4. O 3.628911 0.02 -0.04
end

geometry
convergence 0.000001 0.000001 0.000001
end

unrestricted
charge 0 0

fragments
C t21.C
O t21.O
end

XC
  lda vwn
END

endinput
eor

mv TAPE21 t21.COCO
rm [A-Z]* logfile

mv t21.COCO TAPE21

rm [A-Z]*

rm outplot dostxt
rm TAPE*
rm t21*

Many thanks to the one who can give an explanation for
the error we are encounting!

Kindly
Daniel Bozi (PhD student)

Dept. for Molecular Physics
Chalmers University of Technology
Göteborg, Sweden

Email: bozi_at_fy.chalmers.se
Tel: +46-(0)31-772 45 46
Received on 2001-08-17 15:35:52