Dear Matthew,

It is the Fourier transform of the real space correlations and not energy resolved. For inelastic neutron scattering one needs to measure other quantities and it would indeed be really interesting to add this to a new version of ALPS

Matthias

On 02 Oct 2014, at 20:01, Stone, Matthew B. stonemb@ornl.gov wrote:

ALPS community,

How is the structure factor defined in ALPS? For example, this value can be included in results files using the parameters ‘MEASURE_STRUCTURE_FACTOR[Structure Factor Sz]’ : ‘Sz’.

I am performing calculations using the exact diagonalization and Lanczos ALPS codes for a 1-d chain system. This returns energy levels and momentum such that one can examine the different excitations as a function of energy and wave-vector. I would like to be able to extract parameters for excitations that would be proportional to what is measured in inelastic neutron scattering measurements. This quantity is called the ‘dynamical structure factor’ or the ‘dynamic spin structure factor’ or simply S(q,E). Is the STRUCTURE_FACTOR in ALPS related to this quantity? Or is a sum of the spin-spin correlations more appropriate to use for such a calculation?

Thanks, Matthew Stone