A GRAPHICAL METHOD OF EVALUATING CERTAIN CRYSTALLOGRAPHIC STRUCTURE FACTORS
MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR INSULATION RESEARCH
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A graphical method is described for evaluating structure factor s of the form Fhk o to n of f sub r hk cos 2 pi hx sub r ky sub r and electron density expressions of the form rhoX,Y sum over H sum over K Fhk cos 2 pihX kY. The method depends upon the fact that if in a 2- dimensional001 projection of a unit cell the normal to the planes hk0 is graduated with the appropriate cosine function giving the phases of points along the normal, then a circle, having its center at X2, Y2 and passing through the origin will cut the normal to Fhk0 at the value of cos 2 pihx ky. The practical limitations and general utility of the construction are discussed.