Unitary Coupled Cluster Monte Carlo¶

uccmc {
    sys = system,
    qmc = { ... },
    ccmc = { ... },
    uccmc = { ... },
    restart = { ... },
    reference = { ... },
    logging = { ... },
    output = { ... },
    blocking = { ... },
    qmc_state = qmc_state,
}

Returns:: a qmc_state object.

uccmc performs a coupled cluster Monte Carlo (CCMC) calculation [Filip20] on a system.

Options¶

sys

type: system object.

Required.

The system on which to perform the calculation. Must be created via a system function.

qmc

type: lua table.

Required.

Further options that are common to all implemented QMC algorithms. See qmc options.

ccmc

type: lua table.

Required.

Further options to control the CCMC algorithm. See ccmc options.

uccmc

type: lua table.

Required.

Further options to control the UCCMC algorithm. See uccmc options.

restart

type: lua table.

Optional.

Further options to control restarting the calculation from a previous calculation. See restart options.

reference

type: lua table.

Optional.

Further options to select the reference state used. See reference options.

logging

type: lua table.

Optional.

Further options to enable various logging outputs from a UCCMC simulation. Only available when compiled in debug mode. See logging options for information on current options.

output

type: lua_table.

Optional.

Further options to enable direction of calculation output to a different file. See output options for more information.

uccmc options¶

pow_trunc

type: integer.

Optional. Default: 12.

Polynomial order at which to truncate UCCMC Taylor expansion.

average_wfn

type: logical.

Optional. Default: false.

Whether to print out the average wavefunction sampled over the course of the UCCMC calculation.

trot

type: logical.

Optional. Default: false.

Whether to run a trotterized UCCMC calculation, rather than using the full exponential ansatz.

threshold

type: float.

Optional. Default: \(2^{31}-1\).

The threshold of \(A_C/p_C\), where \(A_C\) is the cluster amplitude and \(p_C\) is the probability of selecting the cluster (exactly like cluster_multispawn_threshold), beyond which a cluster is discarded. This should be bigger than cluster_multispawn_threshold if both are specified.