Algebraic Diagrammatic Construction (ADC) Methods for Core-Excited States
- The algebraic diagrammatic construction (ADC) scheme for polarization propagator is a family of many-body Green’s function methods handling excited states.
- Without the knowledge of propagators, the ADC expressions can be alternatively derived via the intermediate state representation (ISR). In ISR, the n-th order Møller-Plesset (MP) ground state is used as reference and a correlated excited-state basis set can be generated by applying excitation operators on the reference. Thus ADC can be thought as a MP(n) perturbation theory for excited states.
- To access the high-lying core excited state, the core-valence separation (CVS) approximation can be adopted in ADC, in which the coupling matrix elements between the core and valence orbitals are set to zero.
- ADC provide a series of size-consistent, Hermitian, compact and accurate methods for core excited state calculation and X-ray spectroscopy simulation.
ADC simulated and expt. C 1s X-ray absorption spectroscopy of anthracene cation
ADC simulated and experimental O 1s X-ray emission spectroscopy of water