# Hierarchy of equations to calculate the linear spectra of molecular aggregates - Time-dependent and frequency domain formulation

## TL;DR

This paper extends a hierarchy of coupled differential equations for calculating the linear optical properties of molecular aggregates, providing details on numerical implementation and presenting a frequency domain formulation.

## Contribution

It introduces a frequency domain hierarchy and discusses numerical implementation details for the time domain approach.

## Key findings

- Enhanced understanding of numerical methods for hierarchy equations
- Development of frequency domain formulation for optical properties
- Improved computational techniques for molecular aggregate spectra

## Abstract

In a recent publication [J. Chem. Phys. 142, 034115 (2015)] we have derived a hierarchy of coupled differential equations in time domain to calculate the linear optical properties of molecular aggregates. Here we provide details about issues concerning the numerical implementation. In addition we present the corresponding hierarchy in frequency domain.