ERROR: there must be 1 or 3 items on line 2 of POSCAR

[cosmos]

I wanted to optimize the structure of a simple system using the following script:

#!/bin/bash
#BSUB -q parallel
#BSUB -J system
#BSUB -o test.out
#BSUB -n 8
#---- end of options4 to batch queue ----------
#
echo $LSB_HOSTS > machinefile
rm WAVECAR
for i in 4.70, 4.71, 4.72
do
cat >POSCAR <<!
system
$i
0.5 0 0.5
0 0.5 0.5
0.5 0.5 0
1
Direct
0.000, 0.000, 0.000
!
echo "a= $i"
mpirun -nolocal -np 8 -machinefile machinefile vasp
E=`tail -1 OSZICAR` ; echo $i $E >>LATTICE_a.out
done
cat LATTICE_a.out

There was no output in LATTICE_a.out except the three numbers (4.70, 4.71, 4.72). In the test.out file I fount out the error message "ERROR: there must be 1 or 3 items on line 2 of POSCAR".

I have searched this forum and found a related question (The answer was that this problem is due to format error in POSCAR, such as hidden characters). But mine seems different (I did input POSCAR and/or the script manually to make sure there is no hidden characgter), since there is no problem at all if "$i" is put anywhere in the lattice vectors area, e.g. (I did a test on hcp structure)

3.250
1.00 0.00 0.00
-0.5 0.866 0.0
0.00 0.00 $i

Anyone has any clue? Thanks a lot. VASP version is 4.6.31, parallel version.

<span class='smallblacktext'>[ Edited ]</span>

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