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theta-Bragg equals the value of theta Bragg for aQ =
3.5712minus a0 = x. The standard value for theta-Bragg
is calculated first for each affected line. For example,
theta-Bragg for the 931 lines using a lattice parameter of
3.5712Angstroms, is 2.83255 degrees. A lattice parameter
value larger than 3.5712 Angstroms will result in a
smaller theta-Bragg and hence a positive value of delta
theta-Bragg. Likewise, a lattice parameter smaller than
3.5712Angstroms will result in a negative value for delta
theta-Bragg.