Charged systems

[jess_white]

Hi,

I am having issues when changing the NELECT in the INCAR. For instance for Gluconic acid I want it to be -1 and for Co I want it to be 2+. I therefore add or subtract using the ZVAL in the POTCAR to get the NELECT. However for the systems it does not converge and ends up with the error in vasp.log:

-----------------------------------------------------------------------------
| |
| W W AA RRRRR N N II N N GGGG !!! |
| W W A A R R NN N II NN N G G !!! |
| W W A A R R N N N II N N N G !!! |
| W WW W AAAAAA RRRRR N N N II N N N G GGG ! |
| WW WW A A R R N NN II N NN G G |
| W W A A R R N N II N N GGGG !!! |
| |
| The electronic self-consistency was not achieved in the given |
| number of steps (NELM). The forces and other quantities evaluated |
| might not be reliable so examine the results carefully. If you find |
| spurious results, we suggest increasing NELM, if you were close to |
| convergence or switching to a different ALGO or adjusting the |
| density mixing parameters otherwise. |
| |
-----------------------------------------------------------------------------

It does not matter how much I increase the NELM I always get this error. I have attached the input files for both of these systems below. Any help will be greatly appreciated!

[ahampel]

Dear Jess_white,

thank you for reaching out to us on the official VASP forum.

I had a look at your calculation and tried to run them - at least the Co NELECT=7 calculation. The problem is that Co with 7 electrons is an open shell system. And has an atom / molecule with unpaired electrons you most likely always have to add a spin degree of freedom in DFT to get converged results. Hence, with ISPIN=2 your calculation immediately converges, or let's say with NELM=120 or so to any required accuracy. Also making the box slightly asymmetric helps a little bit; Just to break symmetry. Is this a viable solution for you and can you try this also for the Gluconic acid? I would also say that especially for Co the result without ISPIN=2 will be quite wrong, if it converges somehow.

Let me know if that helps.

Best regards,
Alex