# Difference between revisions of "R-factor"

In GED two types of R-factors are in use: structural R-factor (Rstr, sometimes called just R-factor) and experimental R-factor (Rexp).

Structural R-factor is a measure of the agreement between the model and the experimental molecular intensity curves, which are traditionally defined either as sM(s) or s4Im(s).

In case of using sM(s) molecular intensity curves the structural R-factor in percent units is defined as

$R_{str} = \sqrt {\frac{\sum_{i}^{N} \sum_{j}^{M} (sM(s)^{m}_{i,j} - sM(s)^{e}_{i,j})^2}{\sum_{i}^N \sum_{j}^M (sM(s)^{e}_{i,j})^2}} \times 100$

where sM(s)m and sM(s)e are model and experimental molecular intensity curves and summations are performed over all data points of all sM(s) curves. The smaller Rstr the better agreement between model and experimental data. Rstr usually ranges between 1.0 (small molecules and high quality data) and 10.0% (large molecules or low quality data) and depends on the amount of experimental data.

Rstr is equal to RD defined in [MastersSC2013]Author: Masters, SarahL.; Atkinson, SandraJ.; Hölbling, Margit; Hassler, Karl
Journal: Structural Chemistry
Number: 4
Pages: 1201-1206
Title: Gas-phase molecular structure of 1,1,1,2-tetrabromo-2,2-dimethyldisilane: theoretical and experimental investigation of a super-halogenated disilane and computational investigation of the F, Cl and I analogues
Url: http://dx.doi.org/10.1007/s11224-012-0152-6
Volume: 24
Year: 2013
since it does not account for correlations between values in experimental data.