Trace: • 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 *mixture_MAC**.*

**[ mixture_MAC !E]**

Calculates the mass absorption coefficient in cm^{2}/g for a mixture as follows:

_{}where *w*_{i} and (*m**/r*)_{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 are used to calculate *mixture_MAC* and *phase_MAC*.