ARTICLE INFORMATION

All Authors: Sergei N. Yurchenko, J. Tennyson, R. J. Barber, and W. Thiel

Title: Vibrational transition moments of CH4 from first principles

===================

ch4.f90                   a Fortran 90 program to compute the Cartesian dipole 
                          moment components (D) and potential energy values (cm-1) 
                          of CH4 for an arbitrary geometry from the dipole moment 
                          and potential parameters. 
                          The program requires a Lapack subroutine dgells to solve a 
                          3x3 system of linear equation, which can be replaced by any 
                          linear solver. 
                        
ch4_parameters_ai.inp     an input file for ch4.f90  containing the ab initio potential 
                          and dipole moment parameters of CH4. 
                        
ch4_parameters.inp        an input file for ch4.f90  containing the refined potential 
                          and a initio dipole moment parameters of CH4 in a compact 
                          representation (only non-zero parameters are listed). 
                        
tm_ch4.xlsx               an Excel spreadsheet with a list of vibrational transition 
                          moments (D), individual vibrational matrix elements of the 
                          Cartesian components of the dipole moment (D), and vibrational 
                          band intensities (cm-1 atm-2) of 12CH4 at T=298.15K and T=1500K, 
                          all computed using the TROVE approach in conjunction with 
                          a refined PES and ab initio DMS of CH4. The frequency 
                          range 0...10000 cm-1, the upper and lower state energies 
                          are taken below 3000 cm-1 and 8000 cm-1, respectively. 

CH4_TM_S298.15K_S1500K.txt   a rediced ASCII-version of tm_ch4.xlsx which includes 
                          (i) vibrational transition moments (D) and (ii) vibrational 
                          band intensities (cm-1 atm-2)  of 12CH4 at T=298.15K and T=1500K. 


Notations used in the header of the spreadsheet:

 nu / cm-1      transition wavenumber.
 E / cm-1       lower state energy. 
 TM / D         vibrational transition moment defined in Eq.(22).
 S(298.15K)     vibrational band intensity (cm-1 atm-2) for T=298.15K as defined in Eq.(25).
 S(1500K)       vibrational band intensity (cm-1 atm-2) for T=1500K  as defined in Eq.(25).
 G"             symmetry of the lower state. 
 G'             symmetry of the upper state. 
 v"1, v"2,L"2,v"3,L"3,M"3,v"4,L"4,M"4   The lower state normal mode quantum numbers. 
 v'1, v'2,L'2,v'3,L'3,M'3,v'4,L'4,M'4   The upper state normal mode quantum numbers. 
 where v1,v2,v3,v4 are the vibrational quanta, 
 L2,L3,L4 are the vibrational angular momenta (L>0) satisfying Li= vi,vi-2,vi-4..0(1) (i=2,3,4)
 M3,M4 are the projections of L3,L4 on an body-fixed axis with Li>=Mi>=0 (i=3,4).
 <G"_f|M_a|G'_i>  individual matrix elements of a Cartesian component a=x,y,z of 
                  the electronic dipole moment of CH4 as defined in Eq.(21), 
                  where G = A1,A2,E,F1,F2; i,f = x,y,z (F1 and F2) and x,y (E). 






Contact Information:

Sergei Yurchenko
s.yurchenko@ucl.ac.uk
Department of Physics and Astronomy, University College London,
Gower Street, London WC1E 6BT, United Kingdom