The exponent of convergence of poincaré series

This paper continues the systematic study of the exponent of convergence (G) of a Fuchsian groupG begun byA. F. Beardon. The object is to show that in various senses (G) is a continuous function ofG. In view of the incompleteness of our knowledge about (G) considerable attention is paid to illustrative examples.     

Soft rotary mode and structural phase transitions in K2ReCl6

The triple-axis neutron scattering technique has been used to observe the soft-phonon modes associated with the second-order structural phase transitions in the cubic antifluorite K₂ReCl₆. The transverse (ReCl₆)^?2 rotary mode has been found to be soft all along the [ζ00] direction, with the structural distortions being triggered by a condensation first at the zone center and then at the [100] zone boundary. In addition to the soft phonon modes there is a temperature dependent central component to the spectrum along the [ζ00] direction.