  Organic charge transfer salts show a variety of complex phases ranging from
antiferromagnetic long-range order, spin liquid, bad metal or even
superconductivity. A powerful method to investigate magnetism is spin-polarized
inelastic neutron scattering. However, such measurements have often been
hindered in the past by the small size of available crystals as well as by the
fact that the spin in these materials is distributed over molecular rather than
atomic orbitals and good estimates for the magnetic form factors are missing.
By considering Wannier functions obtained from density functional theory
calculations, we derive magnetic form factors for a number of representative
organic molecules. Compared to Cu2+, the form factors |F(q)|2 fall off more
rapidly as function of q reflecting the fact that the spin density is very
extended in real space. Form factors |F(q)|2 for TMTTF, BEDT-TTF and
(BEDT-TTF)2 have anisotropic and nonmonotonic structure.
