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.TH "FCI" "1" "Jan 16, 2019" "2.0" "Quantum Package"
.SH NAME
fci \-  | Quantum Package >
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Selected Full Configuration Interaction with stochastic selection and PT2 .
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.INDENT 3.5
This program performs a CIPSI\-like selected CI using a stochastic scheme for both
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the selection of the important Slater determinants and the computation of the PT2 correction.
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This CIPSI\-like algorithm will be performed for the “n_states” lowest states of the variational space (see \fBdeterminants n_det_max\fP)
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The fci program will stop when reaching at least one the two following conditions:
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.IP \(bu 2
number of Slater determinant > “n_det_max” (see \fBdeterminants n_det_max\fP)
.IP \(bu 2
PT2 < “pt2_max” (see \fBperturbation pt2_max\fP)
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The following other options can be of interest:
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If “read_wf” = False, it starts with a ROHF\-like Slater determinant as a guess wave function.
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If “read_wf” = True , it starts with the wave function(s) stored in the EZFIO folder as guess wave function(s).
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(see \fBdeterminants read_wf\fP)
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If “s2_eig” = True, it will systematically add all necessary Slater determinants in order
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to have a pure spin wave function with an S^2 value corresponding to “expected_s2”.
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(see \fBdeterminants s2_eig\fP and \fBdeterminants expected_s2\fP)
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For excited states calculations, it is recommended to start with a \fBcis()\fP or \fBcisd()\fP guess wave functions
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for the “n_states”, and to set “s2_eig” = True.
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File: \fBfci/fci.irp.f\fP
.SH AUTHOR
A. Scemama, E. Giner
.SH COPYRIGHT
2018, A. Scemama, E. Giner
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