Accurate computations of electron affinity (EA) and ionization potential (IP) are important for predicting properties of molecules, such as redox potentials, band gaps, and photoelectron spectra. Computations of charged excitations (EA/IP) face several challenges associated with the description of charge distribution and open-shell electronic states that require accurate treatment of orbital relaxation and electron correlation effects. In this talk, I will describe an efficient and accurate approach for calculating electron attachment and ionization properties of molecules based on the algebraic diagrammatic construction (ADC) theory (EA/IP-ADC) and its efficient implementation in the PySCF package. I will demonstrate the capabilities of our new implementation by presenting the photoelectron spectrum of the TEMPO radical, as well as the vertical and adiabatic electron affinities of TEMPO and two DNA base pairs (guanine-cytosine and adenine-thymine) computed using the second- and third-order EA/IP-ADC methods. These results demonstrate that the EA/IP-ADC methods are efficient and accurate for simulations of charged excitations and spectra and can be routinely applied to closed- and open-shell molecules with more than 1000 basis functions.

Single-reference algebraic diagrammatic construction theory for electron attachment and ionization and its efficient implementation

ACS Spring Meeting 2021

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