The Pycasino is python implementation of the well-known Casino program.
- supported orbital file formats: gwfn.data, stowfn.data
- using multi-determinant expansions
- capable of doing 3-term Jastrow factor and 3-term Backflow
- configuration-by-configuration (CBCS) and electron-by-electron (EBES) sampling
- partial Ma CUSP correction (no rc optimization yet)
- MPI parallelization
- support VMC and DMC energy calculation, varmin and emin optimization
- pseudopotential
- NEU, NED Number of electrons of up and down spin
- RUNTYPE Type of QMC calculation: vmc, vmc_dmc, vmc_opt
- TESTRUN If this flag is T then read input files, print information and stop
- ATOM_BASIS_TYPE The type of orbitals to be used: gaussian, slater-type
- VMC_EQUIL_NSTEP Number of equilibration steps
- VMC_NSTEP Number of VMC energy-evaluation steps
- VMC_DECORR_PERIOD Number of steps between VMC energy-evaluation moves
- VMC_NCONFIG_WRITE Number of VMC configurations stored for later use in DMC or optimization
- VMC_NBLOCK number of blocks into which the total VMC run is divided post-equilibration
- DTVMC VMC time step (size of trial steps in random walk)
- VMC_METHOD (1) - EBES (work in progress), (3) - CBCS.
- OPT_CYCLES Number of optimization VMC cycles to perform
- OPT_METHOD Optimization method to use: varmin, emin
- OPT_JASTROW Optimize the Jastrow factor in wave-function optimization
- OPT_BACKFLOW Optimize backflow parameters in wave-function optimization
- OPT_DET_COEFF Optimize the coefficients of the determinants in wave-function optimization
- OPT_MAXEVAL Maximum number of evaluations of the variance during variance minimization (default 50)
- OPT_PLAN Allows specifying different parameters for each optimization cycle
- VM_REWEIGHT If set then the reweighted variance-minimization algorithm will be used, else the unreweighted algorithm will be used Unreweighted variance minimization is recommended
- EMIN_METHOD Energy minimization method to use: newton, linear (default), reconf
- DMC_TARGET_WEIGHT Target number of configurations in DMC
- DMC_EQUIL_NSTEP Number of DMC steps in equilibration
- DMC_STATS_NSTEP Number of DMC steps in statistics accumulation
- DMC EQUIL NBLOCK Number of blocks into which the DMC equilibration phase is divided
- DMC STATS NBLOCK Number of blocks into which the DMC statistics accumulation phase is divided
- DTDMC DMC time step
- DMC_METHOD (1) - EBES, (2) - CBCS
- LIMDMC Set modifications to Green’s function in DMC. Only (4) Umrigar mods to drift velocity, Zen–Sorella–Alfè mods to energy
- ALIMIT Parameter required by DMC drift-velocity- and energy-limiting schemes
- NUCLEUS_GF_MODS This keyword is the switch for enabling the use of the modifications to the DMC Green’s function for the presence of bare nuclei
- EBEST_AV_WINDOW Averaging window for calculating the ground-state energy during equilibration (work in progress)
- BACKFLOW Turns on backflow corrections. Backflow parameters are read from correlation.data
- USE_JASTROW Use a wave function of the Slater-Jastrow form. The Jastrow factor is read from correlation.data
- USE_GJASTROW Use gjastrow Jastrow factor. This Jastrow factor is defined in a parameters.casl file (work in progress)
- CUSP_CORRECTION When the cusp correction flag is activated, the s-type Gaussian basis functions centred on each atom are replaced within a small sphere by a function which ensures that the electron–nucleus cusp condition is obeyed
- CUSP_INFO If set then information about how cusp correction is done will be printed to the log-file
- CUSP_THRESHOLD If the magnitude of the s-component of a Gaussian orbital is less than this threshold then it will not be cusp corrected
- NON_LOCAL_GRID Selects the grid for nonlocal integration, can take values between 1 and 7, the default being 4
- LCUTOFFTOL This is used to define the cutoff radius for the local part of the pseudopotential, the default being 1e-5
- NLCUTOFFTOL This is used to define the cutoff radius for the nonlocal parts of the pseudopotential, the default being 1e-5