# Differences

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 m [2009/08/06 15:39]clare created m [2009/08/27 12:16] (current)clare 2009/08/27 12:16 clare 2009/08/06 15:39 clare created 2009/08/27 12:16 clare 2009/08/06 15:39 clare created Line 1: Line 1: ====== m ====== ====== m ====== + + **[//​marquardt_constant//​ !E]…** + + Allows for changing the Marquardt constants, the Simulated_Annealing_1 macro changes the Marquardt constants as follows: + + load marquardt_constant { 0 1 } + + **[//​min_r//​ #] [//max_r// #]** + + Defines the minimum and maximum radii for calculating bond lengths. //min_r// and //max_r// are by default set to 0 and 3.2 Å respectively. + + **[//​mixture_density_g_on_cm3//​ !E]** + + Calculates the density of the mixture assuming a packing density of 1, see also //​[[#​k038|mixture_MAC]]////​.//​ + + **[//​mixture_MAC//​ !E]** + + Calculates the mass absorption coefficient in cm<​sup>​2/​g for a mixture as follows: + + <​sub>​{{techref_files:​image160.gif?​160x45}}​where //​w//<​sub>​i​ and (//​m/////​r//​)<​sub>​i​ is the weight percent and //​phase_MAC//​ of phase i respectively. Errors are reported for //​phase_MAC//​ and //​mixture_MAC//​. + + The following example provides phase and mixture mass absorption coefficients. + + xdd... + + mixture_MAC 0 + + str... + + phase_MAC 0 + + The macros Mixture_LAC_1_on_cm,​ Phase_LAC_1_on_cm and Phase_Density_g_on_cm3 calculates the mixture and phase linear absorption coefficients (for a packing density of 1) and phase density, for example: + + xdd... + + Mixture_LAC_1_on_cm(0) + + str... + + Phase_Density_g_on_cm3(0) + + Phase_LAC_1_on_cm(0) + + Errors for these quantities are also calculated. Mass absorption coefficients obtained from NIST at [[http://​physics.nist.gov/​PhysRefData/​XrayMassCoef|http://​physics.nist.gov/​]][[http://​physics.nist.gov/​PhysRefData/​XrayMassCoef|P]][[http://​physics.nist.gov/​PhysRefData/​XrayMassCoef|hysRefData/​XrayMassCoef]] are used to calculate //​mixture_MAC//​ and //​phase_MAC//​.

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