Is your feature request related to a problem? Please describe.
Previously in #377 the weight setting of the ROG calculation was removed since it was not being used. At the time, it was unclear what the purpose of this was but now we can see that the ROG has some relevance to SANS experiments. It seems like the previous developers must have had this in mind but never implemented it.
According to the Principles of Neutron Scattering from Condensed Matter, the intra-molecular scattering function can be approximated with the Guinier approximation.
where the sum over $j$ go over the atoms of the molecule selected.
Describe the solution you'd like
Add the weight setting to the ROG calculation so that an ROG relevant to SANS experiments can be calculated. We might also need to adjust the job for the case where there is more than one molecule of the same type etc.
Is your feature request related to a problem? Please describe. Previously in #377 the weight setting of the ROG calculation was removed since it was not being used. At the time, it was unclear what the purpose of this was but now we can see that the ROG has some relevance to SANS experiments. It seems like the previous developers must have had this in mind but never implemented it.
According to the Principles of Neutron Scattering from Condensed Matter, the intra-molecular scattering function can be approximated with the Guinier approximation.
$$ P(Q) \simeq \exp(-\frac{1}{3} Q^2 R_{g}^{2}) $$
$$ R{g}^{2} = \frac{1}{B} \int{0}^{\infty} \vert r - r_{\mathrm{com}} \vert^2 n_b (r ) d^{3} r $$
$$ nb (\mathbf{r} ) = \sum{j} \bar{b_j} \delta(r - r_j) $$
$$ B = \sum_{j} \bar{b_j} $$
where the sum over $j$ go over the atoms of the molecule selected.
Describe the solution you'd like Add the weight setting to the ROG calculation so that an ROG relevant to SANS experiments can be calculated. We might also need to adjust the job for the case where there is more than one molecule of the same type etc.