Least-squares refinement of molecular structures from gaseous electron-diffraction sector-microphotometer intensity data. I. Method

; ~ ', An adaptation of the method of least squares to the refinement of molecular structures, based on gaseous electron-diffraction sector-microphotometer intensity data, is presented. The method has the advantages of permitting simultaneous refinement of many more parameters than can be handled by trial-and-error methods and of opening the possibility of obtaining realistic standard errors and error correlations in place of the more subjective 'error limits'. Although the problem of weighting of the observations is not solved, it is felt that the method provides a more straightforward way to take account of factors known to introduce uncertainties than does the alternative approach based on radial distribution functions. A brief account of general experience with the method is given.