Isu dec 10 th
This presentation is the property of its rightful owner.
Sponsored Links
1 / 11

ISU / Dec 10 th PowerPoint PPT Presentation


  • 84 Views
  • Uploaded on
  • Presentation posted in: General

ISU / Dec 10 th. Joaquin Peralta, Rupa Dumpala , and Scott Broderick. First simulations / QE. Quantum espresso Convergence parameters Technical Issues Undefined ‘ input_file ’ to add initial velocities. Defining by modifying source code. Alternatives VASP/QE Coding. Initial Simulations.

Download Presentation

ISU / Dec 10 th

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Isu dec 10 th

ISU / Dec 10th

Joaquin Peralta, RupaDumpala, and Scott Broderick


First simulations qe

First simulations / QE

  • Quantum espresso

    • Convergence parameters

  • Technical Issues

    • Undefined ‘input_file’ to add initial velocities.

    • Defining by modifying source code.

    • Alternatives VASP/QE Coding

Initial

Simulations


Using vasp

Using VASP

  • Available VASP versions : 5.3.2 and 4.X

  • Pseudo potentials

    • PAW – PBE/LDA

    • Alternative of request all-electron (very small number of atoms)

  • Convergence settings

    • Molecules with considerable vacuum space

    • Plane Waves must be around 50% more than the used in classical crystalline structures (RAM memory)

    • Partial occupancies (smearing). In particular for the case of molecules and DM, Fermi-smearing or Gaussian-smearing will be used.

  • Compilation Issues

    • Performance

    • Gamma Point


Si9 cluster

Si9 Cluster

  • Original Adri’s group Si cluster of 9 atoms.

  • Reducing vacuum space size to improve convergence and plane waves.

  • A cubic cell of 30A it was the first option.

  • Silicon first because :

    • Performance Input : ISPIN / ENCUT / NGX

    • Performance Compiling : Gamma Point / Settings

    • Vacuum Space, Plane waves and Memory requirements


Si9 cluster1

Si9 / Cluster

  • Trying to fit best parameters for simulation time

  • Technical issues with

    • Cluster platform fails with NPAR major than eight

    • Compiled version don’t run with a wrong number of NGX, NGY, and NGZ

    • Not considerable performance improvement with more aggressive compilation

  • 1 Ionic step/minute  1fs each step  5ps = 83 hours

  • 1 Ionic step/minute  0.25fs  5ps = 13 days!

* Vasp 5.2.11** The simulation didn’t finish.


Si9 o

Si9 - O

  • Incorporation of Oxygen in the system

  • Using ISMEAR Associated to the temperature of the input file from Adri’s group. T = 338 K

  • Oxygen ENCUT increased the time of the RUN.

  • Technical initial problems / Times

    • Using 64 CPU / NPAR 4  Work ~1 step/min.

    • Using 64 CPU / NPAR 8  Faster, but suddenly simulation stop.

    • Using 128 and 256 CPU

      • NPAR > 8  Simulation faster ~ 1.5 to 2.0 step/min

      • Principal problem, after a couple of hours the simulation stop for different problems

        • Zombie process (Cluster environment problem)

        • Setup ENCUT / NGX / etc.


Si9 o1

Si9 - O


Si9 o2

Si9-O


Si9 o3

Si9-O

  • Temperature response


Isu dec 10 th

Si-9

  • Energy


Next steps

Next steps

  • Reduce vacuum space to improve simulation times.

  • Reduce compiling optimization and disk I/O

    • Cluster problem(s)

    • FFT size grid  Better accuracy, slower simulation time.

  • Based on old NPAR and CPU studies to compare.


  • Login