Next: Parameters
Up: Pass-Band Filtered Trajectory
Previous: Pass-Band Filtered Trajectory
  Contents
Theory and implementation
It is often of interest to restrict attention to motions in a specific frequency interval, both for quantitative analysis
and for visualization by animated display. This is particularly useful to study low-frequency motions without being
distracted by the high frequency "noise". nMOLDYN can create Pass-Band Filtered Trajectory (PBFT) by applying a frequency pass-band filter to the
atomic trajectories, either on the whole system or on an user-defined subset. The result is stored in a new trajectory file that contains only motions in the
chosen interval. Frequency filtering uses a straightforward algorithm:
- take the discrete Fourier transform of each particle trajectory,
- set the Fourier coefficients outside the filtering interval to zero,
- and transform back to the time domain.
This corresponds to applying a rectangular window in the frequency domain.
pellegrini eric
2009-10-06