Search found 28 matches

by sxd375
Sun Mar 29, 2020 5:25 pm
Forum: VTSTTools
Topic: double negative imaginary frequency after dimer run
Replies: 2
Views: 4236

Re: double negative imaginary frequency after dimer run

Hey graeme Thanks for your comments. The vibrational modes are calculated by freezing the surface atoms to save time and just check if the obtained TA state has a single imaginary frequency. I will rerun the dimer calculation as advised and keep you posted. I will check with the linear response meth...
by sxd375
Tue Feb 04, 2020 4:24 am
Forum: VTSTTools
Topic: double negative imaginary frequency after dimer run
Replies: 2
Views: 4236

double negative imaginary frequency after dimer run

Hey Dr. Graeme I have been running dimer method for CO oxidation to CO2 on Pd adatom over ceria 100. However, I am getting significant double negative frequencies on vibration calculation for converged dimer TS structure. Is there anything you would suggest to further refine the dimer run and remove...
by sxd375
Thu Aug 08, 2019 4:29 pm
Forum: VTSTTools
Topic: Dimer calculation -consistent high torque
Replies: 7
Views: 5344

Re: Dimer calculation -consistent high torque

Hey Graeme I agree with the NEB/dimer at cheap settings, however sometimes the reconverging the TS state back to the original settings and higher kpoints take time (I generally use POTIM 0.05/0.1 for reconverging). As for the high torque, I have been getting them on other systems as well. I will see...
by sxd375
Mon Aug 05, 2019 4:46 pm
Forum: VTSTTools
Topic: Dimer calculation -consistent high torque
Replies: 7
Views: 5344

Re: Dimer calculation -consistent high torque

Also found out the following warning errors through out the log files and OUTCAR files. WARNING in EDDRMM: call to ZHEGV failed, returncode = 6 3 4 with different numbers each time during each SCF cycles. The SCF cycles still converge though even after these warnings. Such errors have been suggested...
by sxd375
Mon Aug 05, 2019 3:21 pm
Forum: VTSTTools
Topic: Dimer calculation -consistent high torque
Replies: 7
Views: 5344

Re: Dimer calculation -consistent high torque

Thanks for taking time to converge the dimer. However, as I see - I need to redo a geometric optimisation with the original kpoints and original slab width to get the correct energy. I still do not understand the origin of high torque as I described earlier, though lower kpoints and lower ENCUTs and...
by sxd375
Sun Jul 28, 2019 3:39 pm
Forum: VTSTTools
Topic: Dimer calculation -consistent high torque
Replies: 7
Views: 5344

Re: Dimer calculation -consistent high torque

Dr. Henkelman Thanks for your reply. Yes the SCFs are converging well here. Please find attached the current run below with the input parameters. Just to tell you about the system that I am running it on :it is a PdO on ceria100 surface for CO to CO2 conversion where oxygen from one side are taken t...
by sxd375
Sun Jul 28, 2019 2:17 pm
Forum: VTSTTools
Topic: Dimer calculation -consistent high torque
Replies: 7
Views: 5344

Dimer calculation -consistent high torque

Hi all I have been running a dimer caluclation for TS state (CO to CO2 conversion on ceria 100 surface), however I have been getting consistently high torque which does not drop as the dimer rotates, as below for DROTMAX = 5 (I have tried already with DROTMAX = high values like 50): Step Force Torqu...
by sxd375
Sun May 06, 2018 5:01 pm
Forum: VTSTTools
Topic: Dimer method using IOPT 1 breaks the adsorbate molecule
Replies: 0
Views: 12231

Dimer method using IOPT 1 breaks the adsorbate molecule

Dr. Graeme I have been running dimer for a transition state with LBFGS optimiser, with default values other than INVCURV = 0.005 (I read in the forum, it makes the optimiser rather conservative in taking steps). However, the adsorbate molecule breaks off and drifts apart in some 200th iteration lead...
by sxd375
Fri May 04, 2018 2:55 am
Forum: VTSTTools
Topic: geometric Reoptimise Transition state with original KPOINTS after dimer/NEB
Replies: 3
Views: 6665

Re: geometric Reoptimise Transition state with original KPOINTS after dimer/NEB

OK
As then what do you suggest for re-optimisation if lower POTIM values do not work and higher POTIM takes the strucutre away from the obtained TS state ?

thanks
by sxd375
Thu May 03, 2018 5:42 pm
Forum: VTSTTools
Topic: geometric Reoptimise Transition state with original KPOINTS after dimer/NEB
Replies: 3
Views: 6665

geometric Reoptimise Transition state with original KPOINTS after dimer/NEB

Dr. Graeme As suggested by you in this forum throughout, during a dimer or NEB run approaching forces lesser than 0.1 ev, I lower the constraints on KPOINTS from original to 1 1 1 which lets the run computationally faster and I get the Transition state with this lowered KPOINTS. However, when I try ...
by sxd375
Tue Mar 27, 2018 4:10 pm
Forum: VTSTTools
Topic: curvature turns to positive value - dimer
Replies: 2
Views: 6723

curvature turns to positive value - dimer

Hi Dr. Graeme I have been running dimer calculation from NEB (when the forces dropped to 0.1 ev) with IOPT 3 (deafult values )and 10^-7 EDIFF. However as found below in the DIMCAR (a part of it), the curvature turns to positive value in the 2nd dimer step and remains positive. 1 3.20328 1.19596 -559...
by sxd375
Wed Mar 21, 2018 3:06 pm
Forum: VTSTTools
Topic: dimer method - deviate giving high forces
Replies: 11
Views: 13935

Re: dimer method - deviate giving high forces

Great Thanks
by sxd375
Tue Mar 20, 2018 3:03 pm
Forum: VTSTTools
Topic: dimer method - deviate giving high forces
Replies: 11
Views: 13935

Re: dimer method - deviate giving high forces

Dear Dr. Graeme

please let me know if you have any updates on this.

Thanks
by sxd375
Wed Mar 14, 2018 12:33 am
Forum: VTSTTools
Topic: dimer method - deviate giving high forces
Replies: 11
Views: 13935

Re: dimer method - deviate giving high forces

[quote=sxd375 post_id=9757 time=1520453277 user_id=8521] well Thanks I have another question - can I use IBRION 1 (quasi newton) with low POTIM value and EDIFF 10^-5 in place of IOPT =2 that i am using here( Since IOPT 2 requires curvature calculation and EDIFF 10^-8 requires more running time on th...
by sxd375
Thu Mar 08, 2018 4:14 pm
Forum: VTSTTools
Topic: dimer method - deviate giving high forces
Replies: 11
Views: 13935

Re: dimer method - deviate giving high forces

Sorry to bother u again. I continued the dimer run as posted in the beginning of this thread and I got following DIMCAR with IOPT 2 : Step Force Torque Energy Curvature Angle 1 2.04134 1.05964 -815.09297 -2.71707 1.46944 1 2.04134 0.94002 -815.09297 -2.73440 2.58905 2 2.18434 1.52218 -815.17822 -2.3...