Package: casino
Quantum Monte Carlo packageThe Pycasino program implements some of the methods from the well-knownCasinoprogram.Basic functionalitysupported orbital file formats: gwfn.data, stowfn.datausing multi-determinant expansionscapable of doing 3-term Jastrow factor and 3-term Backflowconfiguration-by-configuration (CBCS) and electron-by-electron (EBES) samplingpartial Ma CUSP correction (no rc optimization yet)use only MPI parallelizationsupport VMC and DMC energy calculation, varmin and emin optimizationList of supported keywords in input fileGeneral keywords:NEU,NEDNumber of electrons of up and down spinRUNTYPEType of QMC calculation: vmc, vmc_dmc, vmc_optATOM_BASIS_TYPEThe type of orbitals to be used: gaussian, slater-typeVMC keywords:VMC_EQUIL_NSTEPNumber of equilibration stepsVMC_NSTEPNumber of VMC energy-evaluation stepsVMC_DECORR_PERIODNumber of steps between VMC energy-evaluation moves.VMC_NCONFIG_WRITENumber of VMC configurations stored for later use in DMC or optimizationVMC_NBLOCKnumber of blocks into which the total VMC run is divided post-equilibrationDTVMCVMC time step (size of trial steps in random walk)VMC_METHOD(1) - EBES (work in progress), (3) - CBCS.Optimization keywords:OPT_CYCLESNumber of optimization VMC cycles to perform.OPT_METHODOptimization method to use: varmin, eminOPT_JASTROWOptimize the Jastrow factor in wave-function optimization.OPT_BACKFLOWOptimize backflow parameters in wave-function optimization.OPT_DET_COEFFOptimize the coefficients of the determinants in wave-function optimization.OPT_MAXEVALMaximum number of evaluations of the variance during variance minimization (default 50).OPT_PLANAllows specifying different parameters for each optimization cycle.VM_REWEIGHTIf set then the reweighted variance-minimization algorithm will be used, else the unreweighted algorithm will be used.
Unreweighted variance minimization is recommended.EMIN_METHODEnergy minimization method to use: newton, linear (default), reconf.DMC keywords:DMC_TARGET_WEIGHTTarget number of configurations in DMCDMC_EQUIL_NSTEPNumber of DMC steps in equilibrationDMC_STATS_NSTEPNumber of DMC steps in statistics accumulationDMC EQUIL NBLOCKNumber of blocks into which the DMC equilibration phase is dividedDMC STATS NBLOCKNumber of blocks into which the DMC statistics accumulation phase is divided.DTDMCDMC time stepDMC_METHOD(1) - EBES (work in progress), (2) - CBCS.LIMDMCSet modifications to Green’s function in DMC. Only (4) Umrigar mods to drift velocity, Zen–Sorella–Alfè mods to energyALIMITParameter required by DMC drift-velocity- and energy-limiting schemes.NUCLEUS_GF_MODSThis keyword is the switch for enabling the use of the modifications to the DMC Green’s function for the presence of bare nucleiEBEST_AV_WINDOWAveraging window for calculating the ground-state energy during equilibration (work in progress).WFN definition keywords:BACKFLOWTurns on backflow corrections. Backflow parameters are read from correlation.dataUSE_JASTROWUse a wave function of the Slater-Jastrow form. The Jastrow factor is read from correlation.dataUSE_GJASTROWUse gjastrow Jastrow factor. This Jastrow factor is defined in a parameters.casl file (work in progress).Cusp correction keywords:CUSP_CORRECTIONWhen 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_INFOIf set then information about how cusp correction is done will be printed to the log-file.CUSP_THRESHOLDIf the magnitude of the s-component of a Gaussian orbital is less than this threshold then it will not be cusp corrected.