A Third-Order Relativistic Algebraic Diagrammatic Construction Method for Double Ionization Potentials: Theory, Implementation, and Benchmark

TL;DR

This paper introduces a third-order relativistic ADC method for double ionization potentials, combining advanced Hamiltonian and integral techniques to improve accuracy and efficiency, validated against experimental and theoretical data.

Contribution

The paper develops a novel relativistic ADC(3) approach using X2CAMF Hamiltonian, Cholesky decomposition, and FNS framework, enhancing computational efficiency and accuracy for DIPs.

Findings

Excellent agreement with fully relativistic four-component results.

Reduced memory and computational requirements.

Validated accuracy against experimental and theoretical data.

Abstract

We present a relativistic third-order algebraic diagrammatic construction (ADC(3)) approach for calculating double ionization potentials (DIPs). By employing the exact two-component atomic mean-field (X2CAMF) Hamiltonian in combination with a Cholesky decomposition (CD) representation of two-electron integrals and the frozen natural spinor (FNS) framework for virtual space truncation, we achieve a significant reduction in both memory requirements and computational cost. The DIPs obtained using the X2CAMF Hamiltonian show excellent agreement with results from fully relativistic four-component calculations. We have validated the accuracy of our implementation through comparisons with available experimental and theoretical data for inert gas atoms and diatomic species. The effect of higher-order relativistic corrections is also explored.