Differences

This shows you the differences between two versions of the page.

--- damp [2010/11/02 01:00] – created pac079
+++ damp [2022/11/03 15:08] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
+====== GSAS-style Dampening Factors ======
+Dampening factor for any refined value (lattice parameters, atomic positions etc.), for those who like to think that they know better than the least squares algorithm.
+<code topas>
+''Rather than the true GSAS dampening [applied shift = (10-damp)/10], an exponential function is used, scaled to useful dampening values of 0-9
+''Useful dampening factors range from values of 0 (no dampening) to 9 (1% applied shift)
+''List of DampFactor,AppliedChanges: 0,1; 1,0.607; 2,0.368; 3,0.223; 4,0.135; 5,0.082; 6,0.50; 7,0.030; 8,0.018; 9,0.011
+''e.g. A simple lattice parameter refinement with dampening factors of 9, 8, 7, 6, 5, 4, 3, 2, 1 and 0
+''     converges in 422, 271, 173, 111, 71, 45, 28, 17, 10 and 5 cycles, respectively
+''Example of use:
+'' site O1	x @  0.30696 Damp(3)	y 0	z 0.25	occ O-2	1	beq @ 2 Damp(7)
+macro Damp(DampFactor)
+{
+   update = Val + (Change*(1/Exp(DampFactor/2)));
+}
+</code>