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Molecular replacement: Difference between revisions
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The intra-molecular vectors would change their orientation (but not their length) when the molecule of the ASU would rotate. For a given rotation of that molecule, only the inter-molecular vectors would change upon translation of the molecule through the ASU. | The intra-molecular vectors would change their orientation (but not their length) when the molecule of the ASU would rotate. For a given rotation of that molecule, only the inter-molecular vectors would change upon translation of the molecule through the ASU. | ||
It is thus clear that it is advantageous to first determine the rotation of the molecule, by restricting the comparison between model patterson and crystal patterson to the intra-molecular vectors. When the correct rotation is found, all vectors may then be used to find the correct translation. | It is thus clear that it is advantageous to first determine the rotation of the molecule, by restricting the comparison between model patterson and crystal patterson to the intra-molecular vectors. When the correct rotation is found, all vectors may then be used to find the correct translation. | ||
== Self-rotation function == | |||
A self-rotation function may be calculated to find the relative rotation between two molecules in the asymmetric unit. It is often calculated in polar coordinates (phi, psi, kappa), because these separate the amount of rotation (kappa) from the axis around which the rotation takes place (phi, psi). | |||
For visualization often a [[stereographic projection]] is used. | |||
== Rotation function (RF) == | == Rotation function (RF) == | ||