Changes relative to https://doi.org/10.17630/sta/872 on St Andrews Research Repository 

2024-05-08
- Added note on citing repository version (Sec. 1.4)
- Updated comment p. 53 degeneracy checks now implemented for PT-TEMPO
- Fixed labelling of diagonal molecular indices in Eqs. 6.2.26, 6.2.29, 6.2.37  

2024-05-11
- Tweaked 'k' subscripted vertical alignment on several photon operators e.g.
  Eq. 6.2.37