Re: [Pw_forum] Convergence problem with Pb180Se180 Cluster optimization

2017-04-21 Thread Narendranath Ghosh
Dear *Prof. Paolo, *Giuseppe*, *ashkan Thank you for your valuable suggestions. After analyzing the structure I think the whole mess is done by surface dangling bonds.Here I don't want to saturate the surface as I have interested to simulate the excitonic and optical properties of the bear

Re: [Pw_forum] Convergence problem with Pb180Se180 Cluster optimization

2017-04-21 Thread Giuseppe Mattioli
> Use more intense kpoint mesh. No, this is useless. 0D systems have molecular-like flat rather than dispersed energy levels in the reciprocal space. There is no reason to sample the Brillouin zone with more k-points. HTH Giuseppe On Friday, April 21, 2017 05:06:42 PM ashkan shekaari wrote:

Re: [Pw_forum] Convergence problem with Pb180Se180 Cluster optimization

2017-04-21 Thread ashkan shekaari
Dear Naren, Increase ecut. Use more intense kpoint mesh. On Apr 21, 2017 4:50 PM, "Giuseppe Mattioli" wrote: > > Dear Naren > Your calculation is very expensive, and calculations of 0D objects in a > plane-wave/PBC framework are often prone to convergence issues.

Re: [Pw_forum] Convergence problem with Pb180Se180 Cluster optimization

2017-04-21 Thread Giuseppe Mattioli
Dear Naren Your calculation is very expensive, and calculations of 0D objects in a plane-wave/PBC framework are often prone to convergence issues. This said, you can try to 1) perform a simple calculation of the PbSe unit cell with the same pseudopotentials. Are there similar convergence

Re: [Pw_forum] Convergence problem with Pb180Se180 Cluster optimization

2017-04-21 Thread Paolo Giannozzi
On Fri, Apr 21, 2017 at 12:36 AM, Narendranath Ghosh wrote: > iteration # 81 ecut=30.00 Ry beta=0.70 >[...] > total energy =2098.58547221 Ry this value is clearly absurd, very likely as a consequence of a wrong structure. Please

[Pw_forum] Convergence problem with Pb180Se180 Cluster optimization

2017-04-20 Thread Narendranath Ghosh
Dear all! I am currently trying to optimizing a Pb180Se180 cluster using QE. But after 83 iterations it didn’t get converged. *Input * calculation='relax', outdir='/staging/op/NAREN_USC/PbSe_360_FINAL_based_Pb68Se68/OUTPUT', prefix='PbSe-360',