CASTEP

Frequently Asked Questions

Licencing

  1. Am I eligible for an academic license and if so what must I do?
  2. If I am not eligible for an academic license, how can I obtain CASTEP?

Getting Help

  1. Where can I get help running CASTEP?
  2. I posted to the CASTEP email list asking for help but nobody answered. What can I do to get an answer?

Getting started

  1. I have a CIF file of my structure. How can I generate input files for CASTEP?

SCF convergence

  1. What SCF solver methods are available in CASTEP?
  2. My SCF failed to converge. What can I do?

Geometry Optimization

  1. How can I check whether my geometry optimization really converged??
  2. My BFGS geometry optimization did not converge. What can I do??
  3. Which geometry optimization method should I use??
  4. Should I trust the "Estimated frequency and bulk modulus" printed by a geometry optimisation??

Bandstructure and DOS

  1. How can I quickly generate a density-of-states plot?
  2. How can I plot partial densities of states?
  3. How can I generate an electronic density of states with the sharp features I expect?
  4. How can I generate a bandstructure plot?
  5. How can I generate a publication quality electronic band structure with the bands properly joined up?
  6. My bandstructure looks a mess with many very short segments.
  7. How can I checkpoint and restart a bandstructure calculation?

Phonon and related calculations

  1. How can I calculate phonons for a spin-polarized system?
  2. How can I do a phonon calculation with DFT+D?
  3. My Raman calculation gives huge numbers or nonsense or "*" characters for the intensity. Why?
  4. How can I perform a "mode-following"calculation explore the energy of a function of amplitude for a particular phonon mode?
  5. I performed a phonon DOS calculation. Do I need to repeat all that calculation if I want dispersion curves as well?
  6. How can I generate a phonon DOS with both sharp and curved features as in textbook examples? I just get a wiggly mess from dos.pl.
  7. How can I compute a phonon projected density of states?

Magnetic resonance calculations

  1. For what kind of molecules and crystals can CASTEP provide reliable NMR predictions?
  2. I completed a NMR ab initio simulation, now how can I compare it with my experimental spectra?
  3. How can I checkpoint and restart a MAGRES calculation?

Pseudopotentials

  1. Which pseudopotential library should I use for functionality which only works with norn-conserving pseudopotentials??
  2. What pseudopotential libraries are available for use with CASTEP??

Postprocessing and Visualisation

  1. How can I create an animation of a geometry optimisation or MD trajectory from my calculation??
  2. How can I create an animation of phonon modes from my calculation??
  3. How can I visualise the results of an NMR chemical shift calculation?
  4. How can I visualise electron density or spin density??

Run-time failure messages

  1. My run aborted with a message of the type "Error XXXX: Failed to open YYYY file"
  2. wave_orthonormalise_overlap_wv_ks: ztrtri failed in inversion
  3. Error writing wavefunction coefficients to file in wave_write_all_par
  4. Error reading wavefunction coefficients from file in wave_read_all_par

Interfacing with other codes

  1. I already have a run set up in Abinit/Quantum Espresso/VASP. How can I set up a similar calculation using CASTEP?
  2. How can I convert my CASTEP run output to use the Henkelman Bader analysis code?

General problems getting a run to work

  1. How should I choose the best number of cores for a parallel run on Archer??
  2. My job stopped before it reached the end. How can I find out how and why it failed??
  3. My HECToR/Archer job fails and the the messages in the PBS log file talk about the "OOM Killer". What does this mean??
  4. How many atoms can I sensibly include in my model??
  5. How can I check my input files do not have a mistake before submitting to the batch queue??
  6. How can I find out how much memory my run will use??

Bugs

  1. I think I found a bug in CASTEP. What should I do?