International
Tables for Crystallography Volume F Crystallography of biological macromolecules Edited by M. G. Rossmann and E. Arnold © International Union of Crystallography 2006 |
International Tables for Crystallography (2006). Vol. F. ch. 25.2, p. 719
|
25.2.4.5.8. Block-diagonal preconditioned conjugate-gradient minimization with pseudoinverses (1998)
With this enhancement, TNT's minimizer treats the second-derivative matrix as a collection of 5 × 5 element blocks along its diagonal, one block for each atom. While this method improves the rate of convergence for noncrystallographic symmetry restraints, its most significant feature is that it allows the refinement of atoms located on special positions without special handling by the user.