Dear George,
a small correction if I may:
However
you will not find TLS in the index, because the credit for
implementing this very useful concept should be given to
Martin Winn, Garib and Ethan, long after the current version
of SHELXL (and its manual) were released in 1997.
Acta Cryst. (*1985*). A41, 426-433
Restrained structure-factor least-squares refinement of protein
structures using a vector processing computer
I. Haneef, D. S. Moss, M. J. Stanford and N. Borkakoti
*Abstract:* A least-squares refinement program /RESTRAIN/ has been
developed, which is capable of refining macromolecular structures using
structure amplitudes, phases from isomorphous replacement or anomalous
scattering and pseudo-energy restraints. In addition to positional
parameters and isotropic temperature factors, anisotropic mean-square
displacements may be refined either as individual atomic *U* tensors or
as *TLS* tensors applied to groups of atoms. Anharmonic effects may be
handled by coupling together occupancies to enable the electron density
of an atomic group to be distributed over more than one subsite. A novel
way of restraining groups of atoms to be planar has been developed that
does not require dummy atoms and does not restrain the plane to lie in
its current orientation.
One can find other, earlier programs, but they are small molecule specific.
Regards,
Pavel.
