Gauge invariance of the coupled cluster oscillator strength

We present an ab initio study of gauge invariance within coupled cluster linear response theory, exemplified by the electric dipole oscillator strength. Through sample calculations using H2, Ne, N2 and H2O as model systems, it is demonstrated that the coupled cluster singles and doubles (CCSD) method, in conjunction with augmented basis sets, provides a reasonable agreement between length, velocity and mixed gauge electronic oscillator strengths.