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# Differences

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+ | **[//marquardt_constant// !E]…** | ||

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+ | Allows for changing the Marquardt constants, the Simulated_Annealing_1 macro changes the Marquardt constants as follows: | ||

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+ | load marquardt_constant { 0 1 } | ||

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+ | **[//min_r// #] [//max_r// #]** | ||

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+ | 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. | ||

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+ | **[//mixture_density_g_on_cm3// !E]** | ||

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+ | Calculates the density of the mixture assuming a packing density of 1, see also //[[#k038|mixture_MAC]]////.// | ||

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+ | **[//mixture_MAC// !E]** | ||

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+ | Calculates the mass absorption coefficient in cm<sup>2</sup>/g for a mixture as follows: | ||

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+ | <sub>{{techref_files:image160.gif?160x45}}</sub>where //w//<sub>i</sub> and (//m/////r//)<sub>i</sub> is the weight percent and //phase_MAC// of phase i respectively. Errors are reported for //phase_MAC// and //mixture_MAC//. | ||

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+ | The following example provides phase and mixture mass absorption coefficients. | ||

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+ | xdd... | ||

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+ | mixture_MAC 0 | ||

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+ | str... | ||

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+ | phase_MAC 0 | ||

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+ | 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: | ||

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+ | xdd... | ||

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+ | Mixture_LAC_1_on_cm(0) | ||

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+ | str... | ||

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+ | Phase_Density_g_on_cm3(0) | ||

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+ | Phase_LAC_1_on_cm(0) | ||

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+ | 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//. | ||