BCS: Bardeen–Cooper–Schrieffer; BRE: bond resonance energy; CHF: coupled Hartree–Fock; CIS: complexation chemicalshifts; CM: centre of mass; CO: common origin; CPT: charge conjugation-parity inversion-time reversal; CSGT: continuous set of gaugetransformations; CSDGT: continuous set of damped gauge transformations; CTDOCD: continuous transformation of the origin of the currentdensity; CTDOCD-DZ: continuous transformation of the origin of the current density, diamagnetic contribution set to zero; CTDOCD-PZ:continuous transformation of the origin of the current density, paramagnetic contribution set to zero; GIAO: gauge-including atomic orbital; HF:Hartree–Fock; HOMA: harmonic oscillator model of aromaticity; HOMO: highest occupied molecular orbital; IGAIM: individual gauges foratoms in molecules; IGLO: individual gauges for localized orbitals; LORG: local origin/localized orbital; MESP: electrostatic potentialtopography; NICS: nucleus-independent chemical shift; NMR: nuclear magnetic resonance; PLL: Pauling–Lonsdale–London; PPP: Pariser–Parr–Pople; QC: quasiclassical; RCM: ring current model; SCF: self-consistent field; TRE: topological resonance energy; TRS: timereversal symmetry; UCHF: uncoupled Hartree–Fock; VB: valence bond.