Find an optimization scheme to obtain DOS curve from SQE, given an initial guess of DOS and a c_ms value

neutrons / multiphonon

multiphonon (getDOS)

MIT License

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Find an optimization scheme to obtain DOS curve from SQE, given an initial guess of DOS and a c_ms value #3

Closed yxqd closed 8 years ago

yxqd commented 8 years ago

The original optimization scheme implemented by max does it by an iterative approach

Start with a initial guess of DOS and a SQE
Calculate SQE of multiphonon scattering
Calculate SQE of multiple scattering using C_ms and multiphonon scattering SQE
Subtract MS and MP SQE from the experimental SQE to obtain single-phonon SQE
Compute a new DOS from the single-phonon SQE
Compare the new DOS to the previous one and calculate the difference
If difference is large, continue the iteration. Otherwise the new DOS is what we want

Prerequisites:

[x] #2
[x] #5
[x] #4

yxqd commented 8 years ago

Should add a step to plot the experimental sqe, the MP sqe, the MS sqe, the corrected sqe, etc

yxqd commented 8 years ago

This looks like mostly working after some bug fixes.

The following are results from working on an ARCS vanadium 300K dataset.

Code:

import histogram.hdf as hh iqehist = hh.load("V-iqe.h5") from multiphonon.sqe import interp iqehist = interp(iqehist, newE = np.arange(-55, 80, 1.)) from multiphonon.backward import sqe2dos sqe2dos.sqe2dos(iqehist, T=300, Ecutoff=65., elastic_E_cutoff=(-12., 6.7), M=50.94, C_ms=0.05, Ei=120.)

Density of States in iterations: dos iterations

S(E) at last iteration: ses

S(Q,E) at last iteration: sqes