Geometric factors of the atom-centred multipole expansion evaluated at a displacement d = r_cavity − R_atom: More...

#include <cosmo_kernel.h>

Public Attributes
double	t0

Vec3	t1

std::array< double, 6 >	t2

double	f3 {1.0}
	Damping factors applied to `t1` and `t2` (1 when undamped) and their derivatives with respect to `rco`.

double	f5 {1.0}

double	df3_drco {0.0}

double	df5_drco {0.0}

Detailed Description

Geometric factors of the atom-centred multipole expansion evaluated at a displacement d = r_cavity − R_atom:

φ = q·t0 + μ·t1 + Σ_p Θ_p·t2[p]

t2 is ordered (xx, xy, yy, xz, yz, zz) — the layout of occ::xtb::CammMoments::qp — and its off-diagonal entries carry the factor of two that the full αβ contraction implies, so each t2[p] is conjugate to the singly-stored component Θ_p. The −tr(Θ)/(3d³) piece is kept so the kernel is the exact expansion for any Θ, not only a traceless one.