The elastic S(q,w) model consists of a list of elastic peaks which are used to simulate Bragg tails. Each line defines a peak, with the columns of each line being: h, k, l, q width, E width, and S.
Here's a sample input file defining three Bragg peaks:
1 0 0 0.002 0.01 0.5
1 1 0 0.002 0.01 1
2 2 0 0.002 0.01 5
This model loads a table of S(Q,w) points in the four-dimensional (Q,E) space and constructs a kd-tree out of it. As with the "elastic model" each line defines one point. The columns are h, k, l, E, and S.
Here's a (very unrealistic) sample input file defining three points.
A realistic input file would include tens of thousands of points to cover
a fine and large enough grid in (Q,E) space.
1 0 0 0 1
1 0 0 0.5 0.5
1 0 0 -0.5 0.5
With the simple phonon model sinusoidal phonon branches can be defined around a given Bragg peak.
In the following input file we define a longitudinal [110] and two
transverse ([001] and [1-10]) branches around the (440) peak:
G = 4, 4, 0
TA1 = 0, 0, 1
TA2 = 1, -1, 0
LA_amp = 25
LA_freq = 0.5*pi/sqrt(2)
LA_E_HWHM = 0.1
LA_q_HWHM = 0.05
LA_S0 = 1
TA1_amp = 15
TA1_freq = 0.5*pi
TA1_E_HWHM = 0.2
TA1_q_HWHM = 0.025
TA1_S0 = 1
TA2_amp = 10
TA2_freq = 0.5*pi/sqrt(2)
TA2_E_HWHM = 0.2
TA2_q_HWHM = 0.025
TA2_S0 = 1
The simple magnon model creates quadratic (ferromagnetic) or linear (antiferromagnetic) branches spherically around a given Bragg peak.
In the following input file we define magnons with a stiffness of D=20 around the
(110) peak:
disp = 0
G = 1, 1, 0
D = 20
offs = 0.
E_HWHM = 0.05
q_HWHM = 0.05
S0 = 1
num_points = 50