Coupled Cluster

CCSD

Fermi.CoupledCluster.RCCSD

Wave function object for Restricted Coupled Cluster Singles and Doubles.

High Level Interface

Run a RCCSD computation and return the RCCSD object:

julia> @energy rccsd

Equivalent to

julia> Fermi.CoupledCluster.RCCSD()

This function calls a constructor that runs a RCCSD computation based on the options found in Fermi.Options.

Fields

Name	Description
`guessenergy`	Energy recovered in the first iteration, normally RMP2
`correlation`	Computed RCCSD correlation energy
`energy`	Total wave function energy (Reference energy + Correlation energy)
`e_conv`	ΔE from the last iteration
`t_conv`	Amplitudes RMS change from the last iteration

Relevant options

These options can be set with @set <option> <value>

Option	What it does	Type	choices [default]
`cc_alg`	Picks RCCSD algorithm	`Int`	[1]
`cc_e_conv`	Energy convergence criterion	`Float64`	[10^-10]
`cc_max_rms`	Amplitudes RMS convergence criterion	`Float64`	[10^-10]
`cc_max_iter`	Max number of CC iterations	`Int`	[50]
`cc_damp_ratio`	Fraction of old amplitudes to be kept	`Float64`	0.0–1.0 [0.0]
`cc_diis`	Whether to use DIIS	`Bool`	`false` [`true`]
`diis_start`	Iteration number where DIIS starts	`Int`	[3]
`cc_diis_relax`	Interval between DIIS extrapolations	`Int`	[3]
`cc_ndiis`	Maximum number of stored vectors for DIIS	`Int`	[3]
`basis`	What basis set to use	`String`	["sto-3g"]
`df`	Whether to use density fitting	`Bool`	`true` [`false`]
`rifit`	What aux. basis set to use for RI	`String`	["auto"]
`drop_occ`	Number of occupied electrons to be dropped	`Int`	[0]
`drop_vir`	Number of virtual electrons to be dropped	`Int`	[0]

Fermi.CoupledCluster.RCCSDpT

Fermi struct that holds information about RCCSD(T) wavefunctions

struct tree:

RCCSD(T) <: AbstractCCWavefunction <: AbstractCorrelatedWavefunction <: AbstractWavefunction