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SHELXL: Difference between revisions
→Refinement of macromolecules with SHELXL
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Despite this generality, it must be emphasized that SHELXL is not suitable for refinements at resolutions lower than about 2.0 Å because, unlike [[Refmac]] and [[PHENIX|phenix.refine]], it does not provide (side-chain) torsion angle restraints, and that a least-squares refinement program such as SHELXL will suffer more from model bias than a program based on maximumlikelihood. Also the Babinet bulk solvent model used in SHELXL is in need of improvement. Almost always the initial refinement will have been performed with another program and SHELXL will be used for the final refinement, perhaps involving extension to very high resolution, modeling of disorder, anisotropic refinement and the least-squares estimation of parameter errors. Thus the starting point for a SHELXL refinement will usually be a PDB format file from the previous refinement. Even when SHELXL has to be used for the refinement of a non-merohedrally twinned structure at lower resolution, the starting model is likely to be in the form of a PDB file from a molecular replacement solution.<br> | Despite this generality, it must be emphasized that SHELXL is not suitable for refinements at resolutions lower than about 2.0 Å because, unlike [[Refmac]] and [[PHENIX|phenix.refine]], it does not provide (side-chain) torsion angle restraints, and that a least-squares refinement program such as SHELXL will suffer more from model bias than a program based on maximumlikelihood. Also the Babinet bulk solvent model used in SHELXL is in need of improvement. Almost always the initial refinement will have been performed with another program and SHELXL will be used for the final refinement, perhaps involving extension to very high resolution, modeling of disorder, anisotropic refinement and the least-squares estimation of parameter errors. Thus the starting point for a SHELXL refinement will usually be a PDB format file from the previous refinement. Even when SHELXL has to be used for the refinement of a non-merohedrally twinned structure at lower resolution, the starting model is likely to be in the form of a PDB file from a molecular replacement solution.<br> | ||
== Input files for SHELXL == | == Input files for SHELXL == | ||