# One-Sided Fourier Transform: Application to Linear Absorption and Emission Spectra

One-Sided Fourier Transform: Application to Linear Absorption and Emission Spectra

One sometimes needs to numerically evaluate the real part of the one-sided Fourier transform of a function . A simple and efficient way to achieve this is to use a fundamental property of the two-sided Fourier transform of a conjugate-even function (i.e., ) and use the efficient fast Fourier transform (FFT) algorithm. This procedure is applied here to the linear absorption and emission spectra of a single excitation interacting with a thermal environment.

f(t)

f(-t)=(t)

*

f