SCO	spin crossover
HS	high spin
LS	low spin
DFT	density functional theory
RASSCF	restricted active space self-consistent field
RASPT2	restricted active space second-order perturbation
CASSCF	complete active space self-consistent field
CASPT2	complete active space second-order perturbation
NEVPT2	N-electron valence state perturbation theory
SORCI	spectroscopy-oriented configuration interaction
CCSD(T)	coupled cluster with single, double and perturbative triple excitations
DMC	diffusion Monte Carlo
GGA	generalized gradient approximation
LDA	local-density approximation
RMSE	root-mean-square error
HF	Hartree–Fock
CBS	complete basis set
CABS	complementary auxiliary basis set
DKH2	Douglas-Kroll-Hess Hamiltonian
CP-PAW	Car–Parinello Projector Augmented-Wave