[ Identification | Description | Input parameters | Links ]
MCViNE_Phonon_IncoherentInelastic_process ComponentS_inc(Q,E) = exp(-2W) hbar^2Q^2/(2M) g(|E|)/|E| [n(E)+1 or n(E)] with the DOS g(E) normalised to 1, Debye-Waller factor computed from the DOS (MCViNE DWFromDOS), and the DOS preprocessed like MCViNE (resampled to >=500 points, parabolic low-energy fit, normalised). The final direction is uniform over 4pi; Ef is uniform in [Ei-Emax_dos, Ei+Emax_dos]. With dEf>0, Ef is restricted to Ef +/- dEf/2 (MCViNE IncoherentInelastic_EnergyFocusing). DOS file: 2 columns E [meV] g(E) (a '#...THz' comment switches the unit to THz) or an MCViNE IDF binary 'DOS' file. Multiphonon terms are not included (see Union IncoherentPhonon_process or NCrystal for those). Union process. Part of the Union components: define this process, collect it into a material with Union_make_material (absorption is set there with my_absorption, the absorption inverse penetration depth at 2200 m/s), assign the material to Union_box/Union_cylinder/Union_sphere/Union_mesh geometries, and add a Union_master after them. Geometry, attenuation and multiple scattering are handled by Union_master; this component provides the MCViNE kernel: the scattering coefficient and the final-state sampling (weight). Isotropic process (powder/liquid-like); rotation is irrelevant. The kernel code is shared with the standalone component MCViNE_Phonon_IncoherentInelastic (mcvine-lib.c). Uses share/mcvine-lib.h/.c and share/mcvine-union-lib.h/.c; the process type MCViNE is declared in share/union-lib.h and registered with Union_master in share/mcvine-union-lib.h. Example: MCViNE_Phonon_IncoherentInelastic_process(dos="MCViNE/Debye_dos.dat", T=300, average_mass=50.94, sigma_inc=10.1, Vc=27.6)
| Name | Unit | Description | Default | |
| dos | str | Phonon DOS file | 0 | |
| T | K | Temperature | 300 | |
| average_mass | amu | Average atomic mass | 0 | |
| Ef | meV | Final energy for energy focusing (used when dEf>0) | 0 | |
| dEf | meV | Full width of the final-energy window; 0 disables focusing | 0 | |
| sigma_inc | barn | Incoherent scattering cross section per unit cell | 0 | |
| Vc | AA^3 | Unit cell volume | 0 | |
| packing_factor | 1 | Packing factor (scales the scattering coefficient) | 1 | |
| interact_fraction | 1 | Union: fraction of interactions forced to this process (-1: by cross section) | -1 | |
| init | string | Deprecated and unused, accepted like on the other Union components (see Union_init). | "" |
| AT ( | , | , | ) RELATIVE | |||
|---|---|---|---|---|---|---|
| ROTATED ( | , | , | ) RELATIVE |
MCViNE_Phonon_IncoherentInelastic_process.comp.
[ Identification | Description | Examples | Input parameters | Links ]
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