Moment distributions of clusters and molecules in the adiabatic rotor model

We present a Fortran program to compute the distribution of dipole moments of free particles for use in analyzing molecular beams experiments that measure moments by deflection in an inhomogeneous field. The theory is the same for magnetic and electric dipole moments, and is based on a thermal ensemble of classical particles that are free to rotate and that have moment vectors aligned along a principal axis of rotation. The theory has two parameters, the ratio of the magnetic (or electric) dipole energy to the thermal energy, and the ratio of moments of inertia of the rotor.Program summaryProgram title:AdiabaticRotorCatalogue identifier:ADZO_v1_0Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADZO_v1_0.htmlProgram obtainable from:CPC Program Library, Queen's University, Belfast, N. IrelandLicensing provisions:Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.htmlNo. of lines in distributed program, including test data, etc.:479No. of bytes in distributed program, including test data, etc.:4853Distribution format:tar.gzProgramming language:Fortran 90Computer:Pentium-IV, Macintosh Power PC G4Operating system:Linux, Mac OS XRAM:600 KbytesWord size:64 bitsClassification:2.3Nature of problem:The system considered is a thermal ensemble of rotors having a magnetic or electric moment aligned along one of the principal axes. The ensemble is placed in an external field which is turned on adiabatically. The problem is to find the distribution of moments in the presence of the external field.Solution method:There are three adiabatic invariants. The only nontrivial one is the action associated with the polar angle of the rotor axis with respect to external field. It is found by Newton's method.Running time:3 min on a 3 GHz Pentium IV processor.