MP1 wavefunction¶
psip_list = mp1_mc {
sys = system,
mp1 = {...},
qmc = {...},
ccmc = {...},
}
- Returns:
- a
particle_t
object.
mp1_mc
creates a deterministic MP1 wavefunction and stochastically coarse-grains (rounds down small amplitudes)
it into a particle_t
object that can be used to initialise a subsequent CCMC calculation. The MP1 wavefunction will be ignored
if restarting from a restart file.
Options¶
sys
type: system object.
Required.
The system on which to perform the calculation. Must be created via a system function.
mp1
type: lua table.
Required.
Further options controlling the calculation.
qmc
type: lua table.
Optional.
If provided, will override the
mp1
input options where relevant.ccmc
type: lua table.
Optional.
If provided, will override the
mp1
input options where relevant.
Note
If you wish to chain together a MP1 calculation and a CCMC calculation, one way to do it would be:
sys = {...}
qmc_opt = {...}
ccmc_opt = {...}
psip_list = mp1_mc{
sys = sys,
qmc = qmc_opts,
ccmc = ccmc_opts,
}
ccmc {
sys = sys,
qmc = qmc_opts,
ccmc = ccmc_opts,
psip_list = psip_list,
reference = {...},
}
Note the lack of commas after the main tables. This makes sure the MP1 wavefunction (the psip_list
object) is compatible
with the subsequent CCMC calculation.
MP1 options¶
D0_population
type: integer.
Required.
Set the initial population on the reference determinant.
Note
This will overwrite the value given in the
qmc
table.state_size
type: integer.
Maximum number of excitors to store in the “main” list, which holds the number of particles on the state and related information such as the diagonal Hamiltonian matrix element. The number of elements that can be stored usually should be of the same order as the target population.
If negative, then the absolute value is used as the maximum amount of memory in MB to use for this information.
Note
This will overwrite the value given in the
qmc
table.real_amplitudes
type: boolean.
Optional. Default: false.
Allow amplitudes to take non-integer weights. This will often significantly reduce the stochastic noise in the Monte Carlo estimates.
Note
This should be the same as the subsequent calculation.
spawn_cutoff
type: float.
Optional. Default: 0.01.
The threshold for stochastic rounding.
rng_seed
type: integer.
Optional. Default: generate a seed from a hash of the time and calculation UUID.
The seed used to initialise the random number generator.
even_selection
type: boolean.
Optional. Default: false.
Note
Must be true if true in the subsequent CCMC calculation.