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# Differences

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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. |
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====== 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. |

- | <code topas>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 | + | <code topas> |

- | '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)</code> | + | '' 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> |