This is a description of the input parameters for xf1f2

datasets: 
	Select a DABAX file from where the f1f2 scattering factors
	will be read. The "all" option is also available, and 
	in this case all datasets are used (useful for comparisons).

material: Select the desired material type. Three options are available:
	a) Element(formula) calculation for a single element. 
	b) Mixture(formula) calculation for a compound or a mixture. The user 
		defines the mixture formula. 
		The syntaxis is the following: string with the chemical
		formula of the compound(s) with their weight fraction between 
		parenthesis.
		Examples:
		H20
		SiO2(0.807)B2O3(0.129)Na2O(0.038)Al2O3(0.022)K2O(0.004)
		H2O(0.99)Cl2(0.01)
		H(0.11189834)O(0.88810166)
	c) Mixture(table) calculation for a compound or a mixture defined
		in the included mixture-table (from dabax file Compounds.dat)

table: Compound table, only available if the c) option in material is chosen.

formula: The element or compound or mixture formula, depending the "material"
		selection.

density: The mixture density in the case that option b) has been
		selected.

calculate: select the calculation magnitude. The "all" option is also 
	available, and in this case all datasets are used (useful for 
	comparisons). The "all" option here is incompatible with the 
	"all" option in the "datasets" entry.


Energy [eV] grid: the abscissas values for the calculations. Two 
		options are available: 
		a) Standard, 100 points in the [0,3] interval.
		b) User-defined, with the parameters described below.
		c) Single-value, with the energy to be entered in 
		   "Starting Energy [eV]" box.

Stating Energy [eV]: the initial energy value (only available if either
		b) or c) is chosen in the "Energy [eV] grid" entry.

To: the last energy value (only available if b) is chosen in the
		"Energy [eV] grid" entry.

Number of points: the number of energy points (only available if b) is 
		chosen in the "sin_theta/lambda grid" entry.

Grazing angle: the surface grazing angle (only available when 
		"reflectivity" calculations are set in "Calculate" entry.
		Two options are available: 
		a) Single-value, for calculations of Reflectivity versus
		   energy.
		b) User-defined, for calculations of Reflectivity versus
		   angle, or reflectivity versus both angle and energy 
		   (2D plot).

Roughness rms [A]: The surface RMS roughness (only available when
		"reflectivity" calculations are set in "Calculate" entry.

Stating Graz angle [mrad]: the grazing angle (when single-value is set) or
		the initial grazing angle value (only available for
		reflectivity calculations).

To: the last grazing angle value (only available if both b) is chosen in the
		"Grazing angle" entry and for reflectivity calculations).

Number of angular points: the number of angle points (only available if both 
		b) is chosen in the "Grazing angle" entry and for reflectivity 
		calculations).

