5.2. Naming conventions in PyBEST

To guarantee the full functionality of PyBEST, especially if you wish to read in your own data files using a format not directly supported by PyBEST, we recommend storing all data in an IOData container exploiting predefined, PyBEST-specific labels. If you work with file formats that are supported in PyBEST and handled by PyBEST internally, you do not need to worry about the naming convention as this is handled automatically.

The following table summarizes all frequently used PyBEST objects, their attribute names in the IOData container, and which LinalgFactory class is typically associated with such an object.

Object	attribute name in IOData	object type	label
list of atoms	atom	list of str or int	–
xyz coordinates [bohr]	coordinates	np.array of float or occ_model.factory.coordinates	–
Occupation model	occ_model	AufbauOccModel	–
Atomic basis set (Gaussian orbitals)	basis or occ_model.factory	Basis	–
kinetic energy integrals	kin	DenseTwoIndex	kin
nuclear attraction integrals	ne	DenseTwoIndex	ne
electron repulsion	eri	DenseFourIndex	eri
		CholeskyIndex	eri
nuclear repulsion	external	float	–
one-electron integrals	one	DenseTwoIndex	one
two-electron integrals	two	DenseFourIndex	two
orbitals	orb_a (restricted/alpha spin)	DenseOrbital	–
	orb_b (beta spin)	DenseOrbital	–
overlap integrals	olp	DenseTwoIndex	olp
electron pair amplitudes	t_p	DenseTwoIndex	t_p
singles amplitudes	t_1	DenseTwoIndex	t_1
doubles amplitudes (may or may not include pairs)	t_2	DenseFourIndex	t_2
\(\Lambda\) for electron pairs	l_p	DenseTwoIndex	l_p
\(\Lambda\) for singles	l_1	DenseTwoIndex	l_1
\(\Lambda\) for doubles (may or may not include pairs)	l_2	DenseFourIndex	l_2
1-RDM	dm_1	(dict of) DenseOneIndex	–
		(dict of) DenseTwoIndex	–
2-RDM	dm_2	dict of DenseTwoIndex	–
		DenseFourIndex	–
3-RDM	dm_3	dict of DenseTwoIndex	–
4-RDM	dm_4	dict of DenseTwoIndex	–
kinetic energy	e_kin	float	–
core energy	e_core (incl. frozen core)	float	–
nuclear attr energy	e_ne	float	–
e_nn	float	–
Coulomb energy (el)	e_hartree	float	–
e_x_hf	float	–
total energy	e_tot	float	–
reference energy	e_ref	float	–
correlation energy	e_corr	float	–
corr energy wrt \(\hat{T}_1\)	e_corr_s	float	–
corr energy wrt \(\hat{T}_p\)	e_corr_p	float	–
corr energy wrt \(\hat{T}_2\)	e_corr_d	float	–
corr energy wrt \(\Omega=0\) of \(\hat{T}_2\)	e_corr_s0	float	–
corr energy wrt \(\Omega=2\) of \(\hat{T}_2\)	e_corr_s2	float	–
corr energy wrt \(\Omega=4\) of \(\hat{T}_2\)	e_corr_s4	float	–