A low-cost four-component relativistic equation of motion coupled cluster method based on frozen natural spinors: Theory, Implementation and Benchmark

TL;DR

This paper introduces a low-cost, four-component relativistic coupled cluster method using frozen natural spinors, enabling efficient and accurate calculation of ionization potentials with controllable precision.

Contribution

It develops a novel method that reduces computational costs for ionization energy calculations while maintaining high accuracy through a natural spinor threshold approach.

Findings

Excellent agreement with experimental ionization energies.

Systematic control of accuracy via natural spinor threshold.

Cost reduction for valence and core-ionization energy calculations.

Abstract

We present the theory and the implementation of a low-cost four-component relativistic equation of motion coupled cluster method for ionized states based on frozen natural spinors. A single threshold (natural spinor occupancy) can control the accuracy of the calculated ionization potential values. Frozen natural spinors can significantly reduce the computational cost for valence and core-ionization energies with systematically controllable accuracy. The convergence of the ionization potential values with respect to the natural spinor occupancy threshold becomes slower with the increase in basis set dimension. However, the use of a natural spinor threshold of 10-5 and 10-6 gives excellent agreement with experimental results for valence and core ionization energies, respectively.