CI::PsiJPi

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Container for CI solutions in a single (J, parity) sector.

Holds the complete set of configuration state functions and the results of the CI diagonalisation for a fixed total angular momentum J and parity.

Construction builds the CSF basis via form_CSFs() but does not solve the eigenvalue problem; call solve() separately after constructing the CI Hamiltonian matrix. Configuration labels are not set automatically – call update_config_info() for each solution after solving.

Note

Only two-electron (two-particle) systems are supported.

#include <CSF.hpp>

Public Member Functions
	PsiJPi (int twoJ, int pi, const std::vector< DiracSpinor > &cisp_basis)
	Constructs the CSF basis for the given J and parity; does not solve.
void	solve (const LinAlg::Matrix< double > &Hci, int num_solutions=0, std::optional< double > all_below={})
	Solves the CI eigenvalue problem for the given Hamiltonian matrix.
void	update_config_info (std::size_t i, const ConfigInfo &info)
	Set configuration info for the ith solution (must be called manually after solve())
const std::vector< CSF2 > &	CSFs () const
	Full list of CSFs spanning this (J, parity) sector.
const CSF2 &	CSF (std::size_t i) const
	Returns reference to the ith CSF.
double	energy (std::size_t i) const
	Energy of the ith CI solution (atomic units)
LinAlg::View< const double >	coefs (std::size_t i) const
	CI expansion coefficients for the ith solution (one per CSF)
double	coef (std::size_t i, std::size_t j) const
	CI coefficient for the ith solution corresponding to the jth CSF.
int	parity () const
	Parity of the sector (+/-1)
int	twoJ () const
	Twice the total angular momentum 2J for this sector.
std::size_t	num_solutions () const
	Number of CI solutions currently stored.
const ConfigInfo &	info (std::size_t i) const
	Configuration info for the ith solution (must have been set via update_config_info())

Constructor & Destructor Documentation

PsiJPi()

CI::PsiJPi::PsiJPi ( int  twoJ, int  pi, const std::vector< DiracSpinor > &  cisp_basis  )

inline

Constructs the CSF basis for the given J and parity; does not solve.

Calls form_CSFs() to build the list of two-electron CSFs. The eigenvalue problem is not solved until solve() is called with the CI Hamiltonian.

Parameters

twoJ	Twice the total angular momentum 2J.
pi	Total parity: +1 or -1.
cisp_basis	Single-particle basis used to construct the CSFs.

Member Function Documentation

solve()

void CI::PsiJPi::solve	(	const LinAlg::Matrix< double > &	Hci,
		int	num_solutions = 0,
		std::optional< double >	all_below = {}
	)

Solves the CI eigenvalue problem for the given Hamiltonian matrix.

Diagonalises Hci and stores the resulting eigenvalues and eigenvectors. Does not populate ConfigInfo; call update_config_info() separately.

• If num_solutions > 0, finds only the lowest num_solutions eigenpairs.
• If all_below is set, finds all eigenpairs with energy below that value (in cm^-1); num_solutions is then ignored.
• If both are unset (or num_solutions <= 0), all eigenpairs are computed.

Parameters

Hci	CI Hamiltonian matrix in the CSF basis.
num_solutions	Number of lowest solutions to find [0 = all].
all_below	If set, find all solutions below this energy (cm^-1).

update_config_info()

void CI::PsiJPi::update_config_info	(	std::size_t	i,
		const ConfigInfo &	info
	)

Set configuration info for the ith solution (must be called manually after solve())

CSFs()

const std::vector< CSF2 > & CI::PsiJPi::CSFs

(

)

const

Full list of CSFs spanning this (J, parity) sector.

CSF()

const CSF2 & CI::PsiJPi::CSF

(

std::size_t

i

)

const

Returns reference to the ith CSF.

energy()

double CI::PsiJPi::energy

(

std::size_t

i

)

const

Energy of the ith CI solution (atomic units)

coefs()

LinAlg::View< const double > CI::PsiJPi::coefs

(

std::size_t

i

)

const

CI expansion coefficients for the ith solution (one per CSF)

coef()

double CI::PsiJPi::coef	(	std::size_t	i,
		std::size_t	j
	)		const

CI coefficient for the ith solution corresponding to the jth CSF.

parity()

int CI::PsiJPi::parity

(

)

const

Parity of the sector (+/-1)

twoJ()

int CI::PsiJPi::twoJ

(

)

const

Twice the total angular momentum 2J for this sector.

num_solutions()

std::size_t CI::PsiJPi::num_solutions

(

)

const

Number of CI solutions currently stored.

info()

const ConfigInfo & CI::PsiJPi::info

(

std::size_t

i

)

const

Configuration info for the ith solution (must have been set via update_config_info())

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The documentation for this class was generated from the following files:

• CI/CSF.hpp
• CI/CSF.cpp