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An idealized molecular geometry library with 40 geometries of molecules and ions optimized by density functional theory methods has been created. All geometries are accessible through a web site. The library entries are tailored for constrained (also known as rigid body) refinements of problematic small-molecule structures with the OLEX2 and SHELXL software packages. The library application is demonstrated with the refinement of a Pd complex, trans-Pd(dimethyl sulfoxide)(OH2)(trifluoroacetate)2, that co-crystallizes in a 2:1 ratio with a solvent molecule of ethyl acetate disordered over an inversion center. Alternative approaches to constrained refinements are discussed.