Hello,

I am studying a particular Perovskite structure. I performed COHP calculation to understand the bond strength. As per the paper mentioned in the manual (PCCP,17,31023-31029 (2015) -"Integration of the COHP diagram is a measure of bond strength (in units of energy)).

But when I perform the COHP analysis and integrated till Fermi level, I am getting a positive value for the integrated COHP, that means the bond is unstable right ?, which is not possible since it is a very well experimentally observed structure. Attached below are the COHP and integrated COHP plot between oxygen and Ni atom within the considered unit cell.

Any suggestions ? I am attaching the input and COHP files from properties calculation.

Thanks in advance for your help !

COHP.dat
INPUT.d3

Regards,
Rams

Hi Giacomo,

Thanks for your reply. I did some test by removing the entire DIIS part, and keeping only the Fock mixing.

• with a FMIXING of 95% the SCF converged in 84 cycles.
• with 70% in 17 cycles
• with the default 30%, it doesn't converges - also the atomic charges were distributed not properly, charges are fully either at the top / bottom layer, and this oscillates between cycle (screenshot below)

--> But this works only with the substrate, for the entire structure with thin film, FMIX of 70% or 95% gives a very similar behavior of charge distribution in 3-4 scf cycles. Only with 99% it moves properly, but that actually means I am practically forcing the system towards the path right ? it may not be a real ground state.

Looking forward towards your opinion and suggestions

Thanks & Regards,
Rams

Hi,

I am trying to simulate a slab model of thin film on substrate. When I ran the job, there was a convergence problem in the SCF cycle. My initial suspect was the interface, since I don't have extract geometrical configuration it was only a pure guess.

So I ran a calculation with only the substrate, but still it did not convergence in SCF cycle with MPPcrystal. I reran the same calculation of only substrate with Pcrystal it converged in 20 cycles. So why is there discrepancy between both versions. I am attaching the input and output for both calculation here.
Substrate_MPP.out
Substrate_MPP.d12
Substrate_Pcrystal.out
Substrate_Pcrystal.d12

To check if there is any issue with the MPP compilation, I added the REPLDATA tag in MPP input, so that it runs as Pcrystal, this time it again converged in 20 cycles.

I would like to use MPPcrystal for my final structure of thin film to speedup the calculation and avoid memory issues, so could you let me what is the issue I am encountering with both the versions.

Thanks & Regards,
Rams

Hi,

I am trying to perform a calculation to compute the defect formation energy. First I performed geometry optimization in Unit cell. Used the optimized structure to make a super cell and removed a particular atom. Due to system size and memory issue with Pcrystal, I used MPPcrystal calcualtion.

The first SCF run was OK (in terms of atomic charges) but due to time limit the calculation was not converged. So I used fort.79 file as initial WF GUESSP to continue the SCF run. But the Total atomic charges is not right, even in the second cycle of the SCF run. As can be seen in output file, the atomic charge change from 8 to 2 in the Run2 output file. Could you kindly guide me regarding my mistake.

Thanks for your help in advance

INPUT_Run1.d12
INPUT_Run2.d12
OUTPUT_Run1.d12
OUTPUT_Run2.d12