DMFT: List of parameters

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Physical parameters

  • U: the Hubbard interaction U
  • BETA: the inverse temperature
  • MU: the chemical potential
  • H: the magnetic field in the quantization axis (conventionally z) direction (BUT: the solvers do ignore the variable!)
  • SITES: number of impurity sites (for DMFT: 1)
  • FLAVORS: number of flavors/orbitals of the impurity (commonly 2: spin up/down)
  • t: in case of Bethe lattice it does provide the hopping (the bandwidth is then W=4t, the half-bandwidth is D=2t); if the option TWODBS is switched on then it does set the nearest-neighbor hopping on the square or hexagonal lattice
  • t0, t1, ...: (available currently only for selfconsistency loop in imaginary time) sets the hopping for the Bethe lattice in multiband case (flavors 2i and 2i+1 share the same parameter ti
  • J: coupling for the multiband problems
  • U': (by default U-2J
  • tprime: applies only if the option TWODBS is switched on and only for the square lattice, then it does set the next-nearest-neighbor hopping
  • TWODBS: (by default sets the square lattice) you may choose either square or hexagonal lattice


Parameters for the self-consistency loop

  • OMEGA_LOOP: set it 1 unless you want to work with semicircular density of states (corresponding to the Bethe lattice in infinitely many dimensions)
  • ANTIFERROMAGNET: if 1 then the antiferromagnetic self-consistency loop will be employed (formula 97 in review '96 of A.Georges et al)
  • SYMMETRIZATION: if 1 then paramagnetic solution is enforced (in versions before 2.1: there has been a misspelling SYMMATRIZATION at several places and a usage of both, SYMMETRIZATION and SYMMATRIZATION, set to the same value was required)
  • MAX_IT: maximum number of iteration in self-consistency loop (usually 10-20 will be enough)
  • CONVERGED: criterium for stopping the self-consistency loop before reaching MAX_IT - if the maximum change in Green's function in Matsubara representation is less than CONVERGED, the loop will stop
  • TOLERANCE: (only for hirschfyesim) as above
  • RELAX_RATE: (by default 1; currently implemented only for selfconsistency loop with OMEGA_LOOP switched on) the new Green's function are in general computed as RELAX\_RATE * G_{new}(i\omega_n) + (1-RELAX\_RATE) * G_{old}(i\omega_n), which may help if oscillations occur


General parameters

  • GENERAL_FOURIER_TRANFORMER: set it on if you have OMEGA_LOOP and other than the Bethe lattice
  • EPS_i: (i=0,1,...,FLAVORS-1) potential shift for the flavor i (necessary for GENERAL_FOURIER_TRANSFORMER)
  • EPSSQ_i: (i=0,1,...,FLAVORS-1) the second moment of the bandstructure for the flavor i (necessary for GENERAL_FOURIER_TRANSFORMER)
  • DOSFILE: sets the name for the file containing the density of states (expected 2 columns with energy value and corresponding density of states at that energy; equidistant energies required; odd number of rows required due to Simpson integration)
  • TWODBS: switches on the Hilbert transformation for 2-dimensional systems, currently supported square lattice (with nearest and next-nearest neighbor hoppings) and hexagonal lattice (with nearest neighbor hoppings) [Note: a different 2-dimensional lattice may be easily added]
  • L: optional parameter available in case of TWODBS is on; defines the half of the linear discretization in the integration in the self-consistency (default: 200)
  • SOLVER: specifies the impurity solver ("Hybridization" or "Interaction Expansion"; the solver "Hirsch-Fye" does suffer from discretization errors and is thus not recommended)


Parameters for the initial/final Weiss field

  • H_INIT: magnetic field in the quantization axis (conventionally z) direction, which is used in computation of the non-interacting initial G0 (if it is not loaded)
  • G0OMEGA_INPUT: name for the text file specifying the Weiss field in Matsubara frequencies i\omega_n (expected 1+FLAVORS columns, and total NMATSUBARA rows) (use only with OMEGA_LOOP)
  • G0TAU_INPUT: name for the text file specifying the Weiss field in imaginary time representation (expected 1+FLAVORS columns, and total N+1 rows) (only with OMEGA_LOOP switched off)
  • GOMEGA_input: specifies the name for the text file where the initial G0 in Matsubara representation will be written (by default it is not written, as it is identical with G0_omega_1)
  • G0TAU_input: name for the text file for the output of the initial G0 in imaginary time (by default it is not written, as it is identical with G0_tau_1)
  • G0OMEGA_output: name for the output file containing the final Weiss field in Matsubara frequencies (by default G0omega_output)(with OMEGA_LOOP)
  • G0TAU_output: name for the output file containing the final Weiss field in Matsubara frequencies (by default G0tau_output) (with OMEGA_LOOP off)
  • INSULATING: if you have specified this option, then the initial G0 will be set up in the insulating limit


Parameters setting the precision of representation of the Green's function and the Weiss field

  • NMATSUBARA: number of Matsubara frequencies used to represent the Green's function and the Weiss field (usually equals N)
  • N: number of bins for the Green's function and the Weiss field in imaginary time (represented in total by N+1 values) (recommended: roughly 1000 for the continuous-time solvers)


Hybridization1 expansion impurity solver parameters

  • MAX_TIME: sets the maximum time given in seconds spent on the impurity problem solving (basically this sets the duration of a single iteration)
  • SWEEPS: number of desired sweeps performed during the calculation (recommendation: set it very high, e.g. 10^9 and the solver will stop on the time limit given by MAX_TIME)
  • THERMALIZATION: number of sweeps before the Monte Carlo measurements in order to reach configuration close to equilibrium (of the order of 1000)
  • EPSSQAV: the second moment of the bandstructure (necessary if you have specified your own DOSFILE)
  • N_ORDER: setting histogram size (if the hybridization order is larger then it will be not stored in the histogram) (value of the order of 100 might be reasonable)
  • N_MEAS: number of Monte Carlo steps between measurements (of the order of 10000)
  • N_SHIFT: number of shifts of segments in a single Monte Carlo step (apparently unused, so 0)
  • MEASURE_FOURPOINT: if switched on then the four-point correlators are being measured
  • N4point: (only used if MEASURE_FOURPOINT is on) description missing so far
  • CHECKPOINT: filename prefix for checkpointing files and for the final h5 and xml output


Interaction expansion1 impurity solver parameters

  • MAX_TIME: sets the maximum time given in seconds spent on the impurity problem solving
  • SWEEPS: number of desired sweeps performed during the calculation (recommendation: set it very high, e.g. 10^9 and the solver will stop on the time limit given by MAX_TIME)
  • THERMALIZATION: number of sweeps before the Monte Carlo measurements in order to reach configuration close to equilibrium (of the order of 1000)
  • SWEEP_MULTIPLICATOR: (default: 1)
  • NRUNS: (default: 1)
  • ALPHA:
  • RECALC_PERIOD: (default: 5000)
  • MEASUREMENT_PERIOD: (default: 200)
  • CONVERGENCE_CHECK_PERIOD: (default provided)
  • ALMOSTZERO: (default: 10^{-16})
  • NSELF: (default: 10N)
  • NMATSUBARA_MEASUREMENTS: (default: NMATSUBARA)
  • HISTOGRAM_MEASUREMENT: (default: false)
  • GET_COMPACTED_MEASUREMENTS:
  • ATOMIC:
  • TAU_DISCRETIZATION_FOR_EXP:
  • CHECKPOINT: filename prefix for the checkpointing files and for the final h5 and xml output


Additional parameters

  • SEED: random seed for the pseudorandom generator
  • RNG: pseudorandom generator used (default is "mt19937"), might be switched to "lagged_fibonacci607"