t
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t [2009/08/06 14:40] – created clare | t [2022/11/03 15:08] (current) – external edit 127.0.0.1 | ||
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+ | ====== t ====== | ||
+ | |||
+ | **[// | ||
+ | |||
+ | **[****// | ||
+ | |||
+ | **[****// | ||
+ | |||
+ | **[****// | ||
+ | |||
+ | **[****// | ||
+ | |||
+ | A temperature regime has no affect unless the reserved parameter name T is used in // | ||
+ | |||
+ | [[# | ||
+ | |||
+ | [[# | ||
+ | |||
+ | // | ||
+ | |||
+ | The reserved parameter T returns the current temperature and it can be used in equations and in particular the // | ||
+ | |||
+ | If < | ||
+ | |||
+ | // | ||
+ | |||
+ | // | ||
+ | |||
+ | // | ||
+ | |||
+ | // | ||
+ | |||
+ | The temperature regime as defined in the macro Auto_T is sufficient for most problems. | ||
+ | |||
+ | A typical temperature regime starts with a high value and then a series of annealing temperatures, | ||
+ | |||
+ | temperature 2 | ||
+ | |||
+ | move_to_the_next_temperature_regardless_of_the_change_in_rwp | ||
+ | |||
+ | temperature 1 | ||
+ | |||
+ | temperature 1 | ||
+ | |||
+ | temperature 1 | ||
+ | |||
+ | If the current temperature is the last one defined (the fourth one), and < | ||
+ | |||
+ | The current temperature can be used in all equations using the reserved parameter T, for example: | ||
+ | |||
+ | x @ 0.123 val_on_continue = Val + T Rand(-.1, .1) | ||
+ | |||
+ | The following temperature regime will allow parameters to randomly walk for the first temperature. At the second temperature the parameters are reset to those that gave the "best solution" | ||
+ | |||
+ | temperature 1 | ||
+ | |||
+ | temperature 1 use_best_values | ||
+ | |||
+ | temperature 1 | ||
+ | |||
+ | temperature 1 use_best_values | ||
+ | |||
+ | temperature 1 | ||
+ | |||
+ | temperature 10 | ||
+ | |||
+ | save_values_as_best_after_randomization | ||
+ | |||
+ | move_to_the_next_temperature_regardless_of_the_change_in_rwp | ||
+ | |||
+ | Note, that when a "best solution" | ||
+ | |||
+ | The following will continuously use the "best solution" | ||
+ | |||
+ | temperature 1 use_best_values | ||
+ | |||
+ | **[// | ||
+ | |||
+ | Used for applying 2q corrections to phase peaks. The following example applies a sample displacement correction: | ||
+ | |||
+ | th2_offset = -2 Rad (c) Cos(Th) / Rs; | ||
+ | |||
+ | // | ||
+ | |||
+ | **[// | ||
+ | |||
+ | // | ||
+ | |||
+ | While // | ||
+ | |||
+ | k = 0 | ||
+ | |||
+ | Do | ||
+ | |||
+ | Change the cation configuration according to // | ||
+ | |||
+ | Find the local minimum of < | ||
+ | |||
+ | If < | ||
+ | |||
+ | k = k + 1 | ||
+ | |||
+ | While < | ||
+ | |||
+ | } | ||
+ | |||
+ | The number of possible cation configurations determines the approximate magnitude of a structure determination problem. A structure consisting of N< | ||
+ | |||
+ | N< | ||
+ | |||
+ | where the notation < | ||
+ | |||
+ | N< | ||
+ | |||
+ | An additional two D sites, or, N< | ||
+ | |||
+ | Here is an example of using // | ||
+ | |||
+ | str... | ||
+ | |||
+ | site Ca... | ||
+ | |||
+ | site Ca... | ||
+ | |||
+ | site Ca... | ||
+ | |||
+ | site Zr... | ||
+ | |||
+ | site Zr... | ||
+ | |||
+ | // | ||
+ | |||
+ | N< | ||
t.txt · Last modified: 2022/11/03 15:08 by 127.0.0.1