Journal
ACTA CRYSTALLOGRAPHICA A-FOUNDATION AND ADVANCES
Volume 72, Issue -, Pages 62-72Publisher
INT UNION CRYSTALLOGRAPHY
DOI: 10.1107/S2053273315022457
Keywords
pair distribution function; organic crystal structures; structure refinement; structure solution
Categories
Funding
- Laboratory Directed Research and Development (LDRD) (Complex Modelling) at Brookhaven National Laboratory (BNL) [12-007]
- US Department of Energy [SC0012704]
- US Department of Energy, Division of Materials Sciences and Division of Chemical Sciences [DE-SC00112704]
Ask authors/readers for more resources
A method towards the solution and refinement of organic crystal structures by fitting to the atomic pair distribution function (PDF) is developed. Approximate lattice parameters and molecular geometry must be given as input. The molecule is generally treated as a rigid body. The positions and orientations of the molecules inside the unit cell are optimized starting from random values. The PDF is obtained from carefully measured X-ray powder diffraction data. The method resembles 'real-space' methods for structure solution from powder data, but works with PDF data instead of the diffraction pattern itself. As such it may be used in situations where the organic compounds are not long-range-ordered, are poorly crystalline, or nanocrystalline. The procedure was applied to solve and refine the crystal structures of quinacridone (beta phase), naphthalene and allopurinol. In the case of allopurinol it was even possible to successfully solve and refine the structure in P1 with four independent molecules. As an example of a flexible molecule, the crystal structure of paracetamol was refined using restraints for bond lengths, bond angles and selected torsion angles. In all cases, the resulting structures are in excellent agreement with structures from single-crystal data.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available