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 damp [2010/11/02 01:00]pac079 created damp [2011/11/25 03:26]rowlesmr fixed some formatting and added additional 's to fix auto colouring. 2011/11/25 03:26 rowlesmr fixed some formatting and added additional 's to fix auto colouring.2010/11/02 08:16 pac079 2010/11/02 01:00 pac079 created Next revision Previous revision 2011/11/25 03:26 rowlesmr fixed some formatting and added additional 's to fix auto colouring.2010/11/02 08:16 pac079 2010/11/02 01:00 pac079 created Line 1: Line 1: ====== GSAS-style Dampening Factors ====== ====== GSAS-style Dampening Factors ====== - Dampening factor for any refined value (lattice parameters, atomic positions etc.), for those who think that they know better than the least squares algorithm + 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. - macro Damp(DampFactor) { update = Val + (Change*(1/​Exp(DampFactor/​2)));​ } + - '​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) + ''​Rather than the true GSAS dampening [applied shift = (10-damp)/​10],​ an exponential function is used, scaled to useful dampening values of 0-9 - '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 + ''​Useful dampening factors range from values of 0 (no dampening) to 9 (1% applied shift) - 'e.g. A simple lattice parameter refinement with dampening factors of 9, 8, 7, 6, 5, 4, 3, 2, 1 and 0 + ''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 - ' ​    ​converges in 422, 271, 173, 111, 71, 45, 28, 17, 10 and 5 cycles, respectively + ''e.g. A simple lattice parameter refinement with dampening factors of 9, 8, 7, 6, 5, 4, 3, 2, 1 and 0 - '​Example of use: site O1 x @  0.30696 Damp(3) y 0 z 0.25 occ O-2 1 beq @ 2 Damp(7)​ + '' ​    ​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)));​ + } +