Localised Orbitals, Periodic Systems and Backflow using CASINO (180' lab)

Neil Drummond and Pablo Lopez Rios

Getting started

1. Log on to tungsten.
2. Type "~train06/install_casino".
3. Type "source ~/.cshrc".
4. Type "rehash".

Directories called CASINO, Silicon_loc, Silicon222, Silicon333 and Neon should have appeared in your home directory. You can now start on the worksheets.

Note that you should use "runqmc nnodes 4 time 00:15" to submit a 15-minute, 4-processor CASINO job on tungsten. (NB, 15 minutes is appropriate for some of the optimisation examples in Worksheet 2; 5 minutes should be fine for the VMC calculations in Worksheet 1.)

Topics

• Worksheet 1: Using localised orbitals in CASINO (1 hour)
  • Brief introduction to CASINO's input files
  • VMC calculations using CASINO
  • Plane-wave and blip representations
  • Localised orbitals
• Worksheet 2: QMC calculations for periodic systems: dealing with finite-size effects (1 hour)
  • Wave-function optimisation
  • Single-particle finite-size effects
  • MPC interaction
• Worksheet 3: QMC calculations using backflow (1 hour)
  • Optimising backflow parameters
  • DMC calculations using CASINO
  • Plotting the backflow transformation