UT theoretical chemistry code forum

I haven't used it in about six years now, but my guess is that the images are moving more slowly than usual since the forces are actually scaled with the number of images in the FPI chain. For that reason the forces are smaller than you might be used to.

No, it is much simpler just to add the "Seletive dynamics" tag to the original POSCAR files. It will not negatively affect your calculations, see http://cms.mpi.univie.ac.at/vasp/vasp/node61.html

Or you can probably delete the extra blank line as well.

You get the blank line since the script wants to read in a "Selective dynamics" line between the line listing number of atoms and "Direct".

Can you post the header of your original POSCAR file?

Because of historical reasons you first need to run vasp2con.pl (as vasp2con.pl CONTCAR) which will generate a CONTCAR.con file. Then use con2xyz.pl on the new .con file.

Plus this implementation uses forward difference while IBRION = 5 uses centered (or higher). So it will require half as many steps to build up the Hessian matrix.

I had to add

use FindBin qw($Bin);
use lib "$Bin";

to the top of the script.

I also made the (unnecessary) following change.

$d12 = `$Bin/dist.pl $d1/POSCAR $d2/POSCAR` ;
# open (DIST, "$Bin/dist.pl $d1/POSCAR $d2/POSCAR |") ;
# $d12 = <DIST> ; close DIST ;

If it works, report back and it ...

Did you download the entire .tar.gz package or just the nebmake.pl script?

Your results look good to me as well. They are for instance very symmetric. Based on the difference in electronegativity, As has a higher value than Si, it may be reasonable to expect As to attract electrons towards it resulting in a 5+ value.

There was a slight error in the code as it was originally implemented and reported in the Comp. Mat. Sci 2006 article. This as now been subsequently been corrected, see the latter two publications at the website (http://theory.cm.utexas.edu/vtsttools/bader). The smaller error you mention is probably ...

It is of course meaningful to search for 2nd order saddle points. The dimer method as implemented in VASP will not however converge to such a saddle since it maximizes the potential energy function in only one degree of freedom while minimizing in all other. You might perhaps get some idea about the ...

How low are the forces in the original band? Is it possible that you are not using the same POTCAR file in the two runs?

Can you post your error?

Have you read through viewtopic.php?f=1&t=368 ? It's a similar system.

Is that with IBRION = 1? Is so, you should really look into using the optimizers developed by the Henkelman group instead. See http://theory.cm.utexas.edu/vtsttools/optimizers/ and JCP , 128(13), 134106, 2008