occ::qm Namespace Reference

quantum mechanics/quantum chemistry functionality including Hartree-Fock and more More...

Namespaces
namespace	basis_sets
namespace	block
namespace	cc
namespace	cint
namespace	cosx
namespace	guess
namespace	impl
namespace	orb

Classes
class	ADIIS
	ADIIS (Augmented Direct Inversion in Iterative Subspace) Based on Hu & Yang, J. More...
struct	AutoAuxResult
	Statistics about the auto auxiliary basis generation. More...
class	CanonicalOrthogonalizer
class	CDIIS
class	ConvergenceAccelerator
	Encapsulates SCF convergence acceleration strategies (CDIIS, EDIIS, ADIIS) More...
class	DFIntegrals
	Builds metric-folded density-fitting "B" tensors for correlated methods. More...
class	EDIIS
struct	Energy
class	GradientEvaluator
class	HartreeFock
class	HessianEvaluator
	Evaluates molecular Hessian matrices (second derivatives of energy) More...
class	IntegralEngine
class	IntegralEngineDF
struct	JKPair
struct	JKTriple
class	MOIntegralEngine
	Lightweight holder of molecular-orbital information for post-HF methods, plus a brute-force single MO electron-repulsion integral evaluator kept as a reference/testing utility. More...
struct	MolecularOrbitals
class	MP2
struct	Oniom
struct	OrbitalSmearing
struct	PointChargePotential
	Plain external point charges (vacuum Coulomb). More...
class	PostHFMethod
struct	SCF
struct	SCFContext
struct	SCFConvergenceSettings
class	SCFMethodBase
class	SplitRIJ
	Split-RI-J: Coulomb matrix via Hermite Gaussian basis (Neese 2003) More...
struct	Wavefunction
struct	WolfPointChargePotential
	Wolf-summed periodic point charges. More...

Concepts
concept	ExternalPotential
	Concept for an external-potential model: a self-contained engine that produces a one-electron potential matrix V_ext and the nuclear–external interaction energy when handed an SCF procedure (HF/DFT/etc.).
concept	SCFMethod
concept	DensityFittingMethod
concept	PointChargeMethod

Typedefs
using	PointChargeList = std::vector< occ::core::PointCharge >
using	DispersionGradientFunc = std::function< std::pair< double, Mat3N >(const AOBasis &, const MolecularOrbitals &, int)>
	Callback that computes a dispersion energy and nuclear gradient for the given basis / orbitals / charge.
using	HessianMatrix = Mat
using	ShellPairList = std::vector< std::vector< size_t > >

Enumerations
enum class	FittingKind { JK , Correlation }
enum class	DispersionType { None , D4 }
enum class	CoulombMethod { Traditional , SplitRIJ }
	Method for computing Coulomb matrix in density fitting. More...
enum class	DiisStrategy { CDIIS , EDIIS_CDIIS , ADIIS_CDIIS }
	Strategy for DIIS extrapolation during SCF. More...
enum class	SpinComponent { Total , Alpha , Beta }

Functions
AutoAuxResult	generate_auto_aux (const AOBasis &basis, double threshold=1e-7, std::optional< int > max_l=std::nullopt)
	Generate automatic auxiliary basis using pivoted Cholesky decomposition Based on Lehtola, J.
Vec	chelpg_charges (const Wavefunction &wfn)
template<SpinorbitalKind kind, typename TA >
TA::Scalar	expectation (const TA &left, const TA &right)
template<typename TA >
TA::Scalar	expectation (SpinorbitalKind sk, const TA &left, const TA &right)
std::string	resolve_fitting_basis (const std::string &orbital_basis_name, FittingKind kind)
int	cosx_nbf_crossover ()
void	from_json (const nlohmann::json &J, Energy &energy)
void	to_json (nlohmann::json &J, const Energy &energy)
std::pair< Mat, Vec >	merge_molecular_orbitals (const Mat &, const Mat &, const Vec &, const Vec &, bool sort_by_energy=false)
AOBasis	merge_basis_sets (const AOBasis &, const AOBasis &)
std::vector< occ::core::Atom >	merge_atoms (const std::vector< occ::core::Atom > &, const std::vector< occ::core::Atom > &)
Vec	mulliken_partition (const AOBasis &basis, const MolecularOrbitals &mo, Eigen::Ref< const Mat > op)
template<SpinorbitalKind sk, Shell::Kind kind>
Mat	shellblock_norm (const AOBasis &basis, const Mat &matrix) noexcept
template<SpinorbitalKind kind>
constexpr std::pair< size_t, size_t >	matrix_dimensions (size_t nbf)
constexpr std::pair< size_t, size_t >	matrix_dimensions (SpinorbitalKind kind, size_t nbf)

Variables
template<typename T >
constexpr bool	is_scf_method_v = SCFMethod<T>
template<typename T >
constexpr bool	supports_density_fitting_v = DensityFittingMethod<T>
template<typename T >
constexpr bool	supports_point_charges_v = PointChargeMethod<T>

Detailed Description

quantum mechanics/quantum chemistry functionality including Hartree-Fock and more

Typedef Documentation

DispersionGradientFunc

using occ::qm::DispersionGradientFunc = typedef std::function<std::pair<double, Mat3N>( const AOBasis &, const MolecularOrbitals &, int)>

Callback that computes a dispersion energy and nuclear gradient for the given basis / orbitals / charge.

Used to inject corrections (e.g. XDM) that live in libraries above occ_qm, so occ_qm need not depend on them.

HessianMatrix

using occ::qm::HessianMatrix = typedef Mat

PointChargeList

typedef std::vector< occ::core::PointCharge > occ::qm::PointChargeList

ShellPairList

using occ::qm::ShellPairList = typedef std::vector<std::vector<size_t> >

Enumeration Type Documentation

CoulombMethod

enum class occ::qm::CoulombMethod

strong

Method for computing Coulomb matrix in density fitting.

Enumerator
Traditional	libcint 3-center integrals (default)
SplitRIJ	MMD kernels using Hermite basis (no atomics)

DiisStrategy

enum class occ::qm::DiisStrategy

strong

Strategy for DIIS extrapolation during SCF.

Enumerator
CDIIS	Standard commutator DIIS only.
EDIIS_CDIIS	EDIIS early, switch to CDIIS when error is small.
ADIIS_CDIIS	ADIIS early, switch to CDIIS when error is small (recommended)

DispersionType

enum class occ::qm::DispersionType

strong

Enumerator
None
D4

FittingKind

enum class occ::qm::FittingKind

strong

Enumerator
JK
Correlation

SpinComponent

enum class occ::qm::SpinComponent

strong

Enumerator
Total
Alpha
Beta

Function Documentation

chelpg_charges()

Vec occ::qm::chelpg_charges

(

const Wavefunction &

wfn

)

cosx_nbf_crossover()

int occ::qm::cosx_nbf_crossover

(

)

expectation() [1/2]

template<SpinorbitalKind kind, typename TA >

TA::Scalar occ::qm::expectation	(	const TA &	left,
		const TA &	right
	)

expectation() [2/2]

template<typename TA >

TA::Scalar occ::qm::expectation	(	SpinorbitalKind	sk,
		const TA &	left,
		const TA &	right
	)

from_json()

void occ::qm::from_json	(	const nlohmann::json &	J,
		Energy &	energy
	)

generate_auto_aux()

AutoAuxResult occ::qm::generate_auto_aux	(	const AOBasis &	basis,
		double	threshold = 1e-7,
		std::optional< int >	max_l = std::nullopt
	)

Generate automatic auxiliary basis using pivoted Cholesky decomposition Based on Lehtola, J.

Chem. Theory Comput. 2021, 17, 6886-6900

matrix_dimensions() [1/2]

template<SpinorbitalKind kind>

constexpr std::pair< size_t, size_t > occ::qm::matrix_dimensions ( size_t  nbf )

constexpr

matrix_dimensions() [2/2]

constexpr std::pair< size_t, size_t > occ::qm::matrix_dimensions ( SpinorbitalKind  kind, size_t  nbf  )

inlineconstexpr

merge_atoms()

std::vector< occ::core::Atom > occ::qm::merge_atoms	(	const std::vector< occ::core::Atom > &	,
		const std::vector< occ::core::Atom > &
	)

merge_basis_sets()

AOBasis occ::qm::merge_basis_sets	(	const AOBasis &	,
		const AOBasis &
	)

merge_molecular_orbitals()

std::pair< Mat, Vec > occ::qm::merge_molecular_orbitals	(	const Mat &	,
		const Mat &	,
		const Vec &	,
		const Vec &	,
		bool	sort_by_energy = false
	)

mulliken_partition()

Vec occ::qm::mulliken_partition	(	const AOBasis &	basis,
		const MolecularOrbitals &	mo,
		Eigen::Ref< const Mat >	op
	)

resolve_fitting_basis()

std::string occ::qm::resolve_fitting_basis	(	const std::string &	orbital_basis_name,
		FittingKind	kind
	)

shellblock_norm()

template<SpinorbitalKind sk, Shell::Kind kind>

Mat occ::qm::shellblock_norm ( const AOBasis &  basis, const Mat &  matrix  )

inlinenoexcept

to_json()

void occ::qm::to_json	(	nlohmann::json &	J,
		const Energy &	energy
	)

Variable Documentation

is_scf_method_v

template<typename T >

constexpr bool occ::qm::is_scf_method_v = SCFMethod<T>

constexpr

supports_density_fitting_v

template<typename T >

constexpr bool occ::qm::supports_density_fitting_v = DensityFittingMethod<T>

constexpr

supports_point_charges_v

template<typename T >

constexpr bool occ::qm::supports_point_charges_v = PointChargeMethod<T>

constexpr