$Id: README,v 1.4 2006/02/21 20:41:28 akohlmey Exp $ This program takes an input file with time-data and calculates the powerspectrum/fourier transform of the autocorrelation function. The input file must only have lines of the form where the first four entries are ignored and the autocorrelation/ fourier-transform is performed on the last 3 entries of a line. The name of the input file as well as other needed quantities are queried by the program interactively. The output file will contain the power-spectrum up to a maximum frequency. The format of this file is: is the frequency in wave numbers. is the plain power spectrum of the input data (normalized to unity in the output frequency range. is the power spectrum with a prefactor of \omega ( 1 - \exp(-\beta \hbar \omega) ) corresponding to the classical/Gordon limit. is the power spectrum with a prefactor of \omega \tanh(\beta \hbar \omega/2) corresponding to the Kubo correction is the power spectrum with a prefactor of \omega \beta \hbar \omega corresponding to the high temperature / harmonic limit Note: this is the recommended correction factor. is the power spectrum with a prefactor of \omega ( 1 - \exp(-\beta \hbar \omega) ) * \exp(\beta \hbar \omega /2) corresponding to Schofield's correction All spectra with their corresponding prefactor are separately normalized in the output range to sum up to unity. Note: the index of refraction of the medium is set to unity. Version 30.4.2002 - H. Forbert harald.forbert@theochem.ruhr-uni-bochum.de changes: 29.01.2005 - A. Kohlmeyer: use simple character arrays for strings. 04.05.2005 - A. Kohlmeyer: more cleanups, split off write routine use xstring() instead of TRIM(), skip over << NEW DATA >> lines, 'port' to several platforms, add dependencies to the makefile. 03.02.2006 - A. Kohlmeyer: added trajec2atoms program to split trajectory files into single atom files that can be run through the fourier code to calculate spectral densisites from velocities. contributed by Robert Williams. 07.02.2006 - A. Kohlmeyer: cleaned up trajec2atoms, added example scripts. 21.02.2006 - A. Kohlmeyer: imported bugfix from 'upstream version'