UT theoretical chemistry code forum

Yves, thanks for the post. This is very good to know. It seems to us that the cube file format is not entirely well-defined. They are written by several codes, and the precise formatting is not the same. We have seen this issue of periodic vs non-periodic file types (with or without the repeated edg...

V2.03d (02/18/09) - module for calculating instantons included (note that the extra object instanton.o is needed in the vasp Makefile) - fixed in a vector projection in the doubly nudged elastic band (thanks to Craig Plaisance) - allow lbfgs for regular (non NEB) optimizations Changes to the followi...

I just want to reiterate our thanks for fixing this bug. This was in a standard function, which could have propagated to other parts of our code.

This doesn't relate to finding transition states; try the general vasp forum for help.

The nebbarrier script needs to get the energies of the initial and final states. It does so from an OUTCAR file in the first (00) and last directories. Our intention is that you copy them from the calculations that were used to make those configurations. But you do not have to use the neb in this wa...

The bin size should be large enough so that you get a significant number of pairs in each bin, but not so large that you lose resolution in your function. The script we provide is very simple and does not try to predict a suitable bin size. Try a few values to find one that is appropriate. The bin s...

(1) Distances between images approaching 2 Angstroms is quite large. It may converge, but for a long path like this, using 6 images would be safer. (2) A linear initial path can be very poor if you have a rotating molecule. You would probably do better by constructing a path yourself. One way to do ...

Check to make sure that your force criteria (ediffg) is smaller than the force on your initial image. Alternatively, you can also set ediffg very small (1e-5 or so). I don't understand how a different version of vasp would change the behavior of our dynamical matrix calculation. Perhaps check to see...

The electronic convergence problem is probably not due to the dimer at all. Try a regular vasp calculation using the same POSCAR file, and you should get the same output for the first electronic steps. There are several reasons that can cause the electronic structure to converge poorly and some solu...

Are you using the PAW potentials? The AECCAR2 is the not same as the CHGCAR.

For simple elementary processes we generally use 3-5 images. While you might get away with a single image, we don't usually do this because it's too much trouble to redo bands using more images if a single image does not converge. Also, using more images gives information about intermediate minima a...

I'm pretty sure this is due to a convention that we have in which the first line of your POSCAR or CHGCAR file should be the elements used in the calculation. Try changing your first line from

FeN Oct Bulk Calc

to

Fe N

You will not be able to accurately integrate the total charge density because of the cusps at the atomic centers. Instead, use the total charge to do the partitioning and the integration on the valance charge density. These values will converge with modest grid sizes. To do this, follow the instruct...

It's very simple: the ACF.dat file has the charge for each atom listed in a table.

No, I think that something is very strange. These charges are far too large to make sense.

Are you using vasp5? This new version has a slightly different format and is not read properly by our program yet.

If you can make the file available to use, we'll take a look at it.