Hi Eleanor Electron scattering factors can be negative for negative ions, particularly at low d*. For a low-resolution map it means that the electric potential is the opposite sign to what you expected. It's why you often don't see ASP & GLU side-chains in low resolution EM maps.
Cheers -- Ian On 15 March 2018 at 14:17, Eleanor Dodson < 0000176a9d5ebad7-dmarc-requ...@jiscmail.ac.uk> wrote: > I am pig-ignorant about these ,, but this example has negative values as > well as positive.. > > What does this mean? I thought a well phased map would be pretty well all > positive.. > > Eleanor >
