UT theoretical chemistry code forum

If you write the chgcar and/or wavecar, these get compressed and moved to the directory you specify in the vfin.pl argument. But as it is, we don't leave copies of these files for restarting. They can help speed up the first iteration, but I guess we don't find the speed savings worth the extra disk...

This sounds a little puzzling. Our scripts simply grep for the energy in the OUTCAR file. Can you send a .tar.gz file of the run, and say which energy you think is incorrect? Can you also make sure that your single calculation has the same parameters as the neb calculation. The parameters in the INC...

Thanks, that's good to hear.

I have an off-topic question. As one of the few people who have used both vasp and dacapo extensively, how do they compare in efficiency? Do you notice significant differences when finding transition states?

That's good to hear. It sounds like POTIM was the source of the problem. If you care most about the energy barrier, you can find the energy difference between the saddle point and your initial state. You can also use our scripts: vfin.pl dir cd dir nebresults.pl which will archive your run into the ...

A POTIM of 0.35 is larger than I usually use, but it may not be the problem.

To sort out what's going on, it would help to look at your run. If you are willing to send me a .tar.gz file of your 60 ionic step run, I'll take a look at your settings, and see if I can make any suggestions.

This simple script has been updated to work for both poscar and con files. Periodic boundary conditions and non-orthogonal cells are also properly treated. Thanks to Yuri Mastrikov for pointing out this problem. Well, it would be better to say that distances in periodic systems are treated in the sa...

What you have done is fine. You can generate an neb using nebmake.pl and run the standard vasp code and find a converged minimum energy path. The source files in vtstcode.tar.gz provide transition state extensions to the vasp code. These source files can be built and linked into the vasp program. Th...

You can turn on the climbing image with the double nudging. I suggest adding the tag LCLIMB=.TRUE. It would be interesting to start your calculation after you did a few IBRION=3 steps, and compare how long it takes to converge using the climbing image and double nudging, with your original calculati...

Sure, I've updated the vtstcode.tar.gz file on the page:

http://theory.cm.utexas.edu/vtsttools/code/

There are also any number of free programs that allow you to access cvs servers through windows, both graphical and from the command line.

I think it's fine to do a few steps using a small time step, but I recommend turning on the climbing image right afterwards. I don't think it makes sense to converge the neb without climbing image and then turn it on. Also, if you are willing to try a new method, we would be very interested to see i...

Non-orthogonal cells should be properly treated in the version of the code which is in cvs. cvs -d :pserver:anonymous@theory.cm.utexas.edu:/Groups/cvs login cvs checkout bader use the password 'anonymous' when prompted. We're in the process of making significant changes to the code, but the original...

The variable VTST_ZIP can be set to gzip (the default) or bzip2. The later tends to have a higher compression ratio.

1) I can't see a situation that would result in a saddle point with an energy less than the initial minimum. By definition, the initial state should be reached by minimizing from the saddle point. That said, within the general transition state theory, you can choose a valid transition state (an N-1 ...

It's actually the highest energy image which is moved up in energy to the saddle point. This would typically be the image which is closest to the extrema of highest energy, but the two definitions are not the same. (I think they are the same only for a harmonic potential at the saddle). I have never...

The climbing image is only used for the highest energy image along the path. In principle, the algorithm could be applied to any local maximum (and/or minimum) along the path, but we have done this with the implementation in vasp. Usually when an intermediate minimum is found, it's easier to minimiz...