UT theoretical chemistry code forum

In the neb code the reaction coordinate is defined at every image to be energy based upwinding tangent. At the maximum image the tangent is an energy weighted average of the vectors from and to the previous and next image. JCP 113, 9978 (2000) The dimer and other mini-mode methods define the reactio...

Thanks for bringing that to light, I just added an additional character to the print statement so it should now handle 3 characters before the decimal before running together. This should pretty robustly cover all standard box sizes and shapes.

It has potential to help the cg routine however it has not yet been implemented for it. There would be no advantage to adding the tag to QM, SD, or FIRE

If you are just interested in finding minima I would use a method like basin hopping where you make a random kick and then minimize. If however you want to find connected states and kinetic information you could use dimer searches to find all relevant saddles around a minima and then run a steepest ...

Are all atoms in the system free to move? Could be the same local minima with just a translation or rotation? This would lead to the appearance of two adjacent local minima without a transition state between the two.

There so be no issue for a path where an atom that leaves one side of the cell and enters the other. This being said atom 1 in image 1 must always be atom 1 in image 2.

I don't think so. If there is really no saddle try tightening the convergence criteria and see if both minima converge to a single minima.

By metastable do you mean the NEB found an intermediate minima? - If this is the case I would stop the calculation, converge the intermediate, sand then start two NEBs connecting state 1 to the intermediate and then the intermediate to state 2. If by metastable you mean you have found a shoulder and...

There seems to be a typo in you INCAR

OPTIM = 0

should be
POTIM=0

This will make sure you are not taking two steps for every force

Dan

The bug fixed in 2.03b for "regular" runs had to do with optimization methods that used a finite different step. The neb was checked for convergence before moving the ions. This was not the case when doing a regular geometry optimization of a single configuration. All of the IOPT optimizer...

I am going to have to disagree. To add a falling image would hurt convergence. It would pull images away from the saddle possibly compromising the tangent of the saddle. Not to mention a system that has in intermediate minima has multiple saddle points so it would require multiple climbing images. A...

pratyush had a good idea but this change will affect the proper writing of POSCAR files that contain the selectiveflag.

There were two bugs dealing with this. One in read_poscar and one in write_poscar. I have updated the vtstscripts with fixes to these bugs

radial distribution function usage: rdf.pl <POSCAR filename> <atom to measure from> <bin size in Angstroms> The output printed to the screen is but can be piped to a file and has the format distance, ( frequency ) : list of atoms included in bin You can plot a histogram of the rdf by then using the ...

chg2cube.pl has been updated to handle vasp5 and the optional comment line. It can be obtained from cvs

Dan

The top line in vasp4 CHGCAR is an optional comment line, our group by convention uses this line to include element types. However because the cube format uses atomic numbers instead of element names so the script was not written to accommodate anything but a blank comment line or no comment line. T...