title: Chemical shift driven geometry optimization.
abstract: A new method for refinement of 3D molecular structures by geometry optimization is presented. Prerequisites are a force field and a very fast procedure for the calculation of chemical shifts in every step of optimization. To the energy, provided by the force field (COSMOS force field), a pseudoenergy, depending on the difference between experimental and calculated chemical shifts, is added. In addition to the energy gradients, pseudoforces are computed. This requires the derivatives of the chemical shifts with respect to the coordinates. The pseudoforces are analytically derived from the integral expressions of the bond polarization theory. Single chemical shift values attributed to corresponding atoms are considered for structural correction. As a first example, this method is applied for proton position refinement of the D-mannitol X-ray structure. A crystal structure refinement with 13C chemical shift pseudoforces is carried out.
authors.affiliation: PAF/IOQ/HF, Friedrich Schiller University Jena, Germany. witter@ioq.uni-jena.de
authors.forename: Raiker
authors.initials: R
authors.lastname: Witter
authors.forename: Wolfram
authors.initials: W
authors.lastname: Priess
authors.forename: Ulrich
authors.initials: U
authors.lastname: Sternberg
mesh_terms: D002236:Carbohydrate Conformation; D002247:Carbon Isotopes; D018360:Crystallography, X-Ray; D008280:Magnetics; D008358:Mannose / Q000737:chemistry; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular
chemical_list: D002247:Carbon Isotopes; D008358:Mannose