Module basis 

Atomic orbital basis representations: STO and contracted Gaussian (STO-nG).

Provides Slater-type orbitals (STOs) and their expansion into Gaussian primitives for tractable overlap-integral evaluation.

Structs

AtomicOrbital

A single atomic orbital in the molecular basis, located on a specific atom.

GaussianPrimitive

A single Gaussian primitive: coefficient × exp(-alpha × r²).

SlaterOrbital

A Slater-type orbital represented conceptually.

Functions

build_basis

Build the full molecular basis set from atom positions (in Angstrom) and elements. Positions are converted internally to bohr for consistency.

gaussian_p_value

Evaluate a normalized p-type Gaussian component: N × x × exp(-α r²). component is the Cartesian displacement (x, y, or z) from the center.

gaussian_s_value

Evaluate a normalized s-type Gaussian (2α/π)^{3/4} exp(-α r²) at distance² r2.

sto3g_expansion

Build STO-3G Gaussian primitives for an orbital with given n, l, and ζ.