Solving Response Expressions in the ADC/ISR Framework

23 December 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


We present an implementation for the calculation of molecular response properties using the ADC/ISR approach up to third order. For second order ADC(2), a memory-efficient ansatz avoiding the storage of double excitation amplitudes is investigated. We compare the performance of different numerical algorithms for the solution of the underlying response equations for ADC(2) and show that this memory-efficient ansatz strongly improves the convergence behavior for the investigated algorithms. All routines are implemented in an open-source Python library.


theoretical chemistry
response theory
molecular properties

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