Search found 2255 matches
- Wed Apr 09, 2008 3:52 am
- Forum: Bader
- Topic: zero bader charge!
- Replies: 4
- Views: 51523
Re: zero bader charge!
You need to add core charges. See: http://theory.cm.utexas.edu/bader/vasp.php
- Tue Apr 08, 2008 3:03 pm
- Forum: VTSTTools
- Topic: NEB basic questions
- Replies: 3
- Views: 10710
Re: NEB basic questions
The images can become unequally spaced if you are using the climbing image. But if the saddle is between your widely spaced images, it sounds like something is wrong. Similarly for a linear band that converges right away - something is wrong. But I can't tell what's wrong without more information; i...
- Tue Apr 01, 2008 12:24 am
- Forum: Bader
- Topic: ECP in Gaussian and feature suggestion
- Replies: 2
- Views: 9524
Re: ECP in Gaussian and feature suggestion
We have struggled with a similar problem with pseudopotentials in VASP. The code can deal with this in a fairly simple way by associating each Bader volume with the nearest atomic center. But, if the charge density minimum between atoms is missing, there will be no maximum near atomic centers. In th...
- Wed Mar 19, 2008 2:11 am
- Forum: Bader
- Topic: For gga POTCAR
- Replies: 1
- Views: 6506
Re: For gga POTCAR
1. In order to get core charges, you need the latest version of vasp and must use the PAW potentials (which can be used with GGA). The core charges are not always essential, but it makes the analysis much better. 2. A good first guess is to use a grid that is twice as dense as the default value prin...
- Wed Mar 05, 2008 2:32 am
- Forum: VTSTTools
- Topic: error on website for dimer method
- Replies: 3
- Views: 8871
Re: error on website for dimer method
Ah, I think I see the problem. Let me summarize and try another modified description - the code is doing what I want it to do. if (FNr < FNMin): do not rotate, pass control back to the optimizer if (FNMin < FNr < FNMax): do at least 1 rotation if (FNr > FNMax): rotate until FNr<FNMax or the number o...
- Tue Mar 04, 2008 9:16 pm
- Forum: VTSTTools
- Topic: Dimer method - convergence criteria
- Replies: 1
- Views: 6724
Re: Dimer method - convergence criteria
This is a good point. The Dimer method uses a force criteria to quit, and does not demand that the minimum curvature be negative. To search for a saddle starting from a minimum, it is essential to perturb the system away from the minimum so that the forces are above the convergence criteria. If this...
- Sat Mar 01, 2008 4:39 pm
- Forum: VTSTTools
- Topic: error on website for dimer method
- Replies: 3
- Views: 8871
Re: error on website for dimer method
I guess I don't quite understand the issue - do you think that the Min/Max description in the variables is misleading, or are you saying that there is an error in the implementation? I've tried to clarify the variable descriptions: DFNMin: Magnitude of the rotational force below which rotation stops...
- Sat Mar 01, 2008 4:05 pm
- Forum: VTSTTools
- Topic: Interstitialcy mechanism
- Replies: 2
- Views: 7674
Re: Interstitialcy mechanism
Besides trying to determine a final state from your intuition about the reaction mechanism, you could either run dynamics at a high temperature to find nearby minima, or run min-mode following saddle point searches from your initial state.
- Sat Feb 23, 2008 3:36 pm
- Forum: Bader
- Topic: Can bader handle a molecule standing on the box edge?
- Replies: 1
- Views: 6498
Re: Can bader handle a molecule standing on the box edge?
It should be fine. We assume periodic boundary conditions in the analysis.
- Fri Feb 15, 2008 10:38 pm
- Forum: Bader
- Topic: RCORE vs MIN DIST
- Replies: 12
- Views: 27683
Re: RCORE vs MIN DIST
Ok, it's good that you are using the core charge. Now, what exactly are you concerned about: the difference in the V/Ti/Sc as you go from the _pv to _sv potentials (0.01-0.02 e), or that Rcore is less than Min Dist? If the former, I would suggest that this is related to the systematic error intrinsi...
- Fri Feb 15, 2008 9:01 pm
- Forum: Bader
- Topic: RCORE vs MIN DIST
- Replies: 12
- Views: 27683
Re: RCORE vs MIN DIST
It is now possible to write the core charges within vasp. This essentially eliminates the core charge problem. There are instructions about how to do this on the page http://theory.cm.utexas.edu/bader/vasp.php With core charges, the analysis should not be particularly sensitive to how many electrons...
- Fri Feb 15, 2008 6:46 am
- Forum: VTSTTools
- Topic: dimer method can not start.
- Replies: 8
- Views: 21783
Re: dimer method can not start.
Good to hear that this was solved. That run looks just fine.
Do you know why MPI_CHAIN was set in the makefile? Was this in one of the makefiles supplied by the vasp group?
Do you know why MPI_CHAIN was set in the makefile? Was this in one of the makefiles supplied by the vasp group?
- Sat Feb 02, 2008 6:38 am
- Forum: VTSTTools
- Topic: dimer method can not start.
- Replies: 8
- Views: 21783
Re: dimer method can not start.
I'm still not sure what's going wrong. Can you run a standard parallel vasp calculation, or a regular NEB run? You could try updating to the latest vasp.4.6.31 08Feb07, but I don't have any reason to believe that this will change anything. Are there any clues in the OUTCAR? Do you see a line with VT...
- Sat Feb 02, 2008 6:07 am
- Forum: VTSTTools
- Topic: about dynamical matrix calculation
- Replies: 9
- Views: 19874
Re: about dynamical matrix calculation
This is certainly slow convergence, but the numbers at this point look reasonable. As long as the 5th column remains negative, and forces (2nd column) remain small, it is likely near a saddle. Take a look at the XDATCAR (you can use xdat2xyz.pl to see a movie, or using vmd) to make sure that the geo...
Re: FFT grid
There are two separate issues here. First, do the Bader charges converge with respect to the grid density. Second, do the results make sense. We would be concerned if the analysis does not converge. If you can not get well defined charges with a fine grid, that is a problem. If the results are not w...