CCP4 web logo Basic Maths for Protein Crystallographers
Resolution
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The length of the reciprocal lattice vector ha*+kb*+lc* is called d* and equals 2sinthetaoverlambda.
Crystallographers often define S as (d*)² or 4sinsqthetaoverlambdasq.
Protein crystallographers talk about resolution in terms of 1/d* (or d), hence the 'high resolution' limit is actually a small number.