Calculation Without Data: Si, TOF¶

This example shows how to calculate and plot a time-of-flight diffraction pattern without any measured data. As with the constant-wavelength example, the structure, instrument, peak profile, and background are defined in code, and the pattern is computed over a calculation range.

For a time-of-flight instrument an absolute time window is meaningless without a calibration, so the default data_range is derived from the instrument's TOF calibration. No data file is downloaded or loaded.

For this example, a time-of-flight neutron powder experiment for Si is used.

🛠️ Import Library¶

In [2]:

import easydiffraction as edi

import easydiffraction as edi

📦 Define Project¶

In [3]:

project = edi.Project(name='si_simulation')

project = edi.Project(name='si_simulation')

🧩 Define Structure¶

In [4]:

project.structures.create(name='si')

project.structures.create(name='si')

In [5]:

structure = project.structures['si']

structure = project.structures['si']

In [6]:

structure.space_group.name_h_m = 'F d -3 m'
structure.space_group.coord_system_code = '2'

structure.space_group.name_h_m = 'F d -3 m' structure.space_group.coord_system_code = '2'

In [7]:

structure.cell.length_a = 5.431

structure.cell.length_a = 5.431

In [8]:

structure.atom_sites.create(
    id='Si',
    type_symbol='Si',
    fract_x=0.125,
    fract_y=0.125,
    fract_z=0.125,
    adp_iso=0.5,
)

structure.atom_sites.create( id='Si', type_symbol='Si', fract_x=0.125, fract_y=0.125, fract_z=0.125, adp_iso=0.5, )

In [9]:

project.display.structure(struct_name='si')

project.display.structure(struct_name='si')

Structure 🧩 'si' (Atom view type: 'covalent')

Loading plot…

drag = rotate
wheel = zoom
right-drag = pan

🔬 Define Experiment¶

Create Experiment Without Data¶

In [10]:

project.experiments.create(
    name='sim',
    sample_form='powder',
    beam_mode='time-of-flight',
    radiation_probe='neutron',
)

project.experiments.create( name='sim', sample_form='powder', beam_mode='time-of-flight', radiation_probe='neutron', )

In [11]:

experiment = project.experiments['sim']

experiment = project.experiments['sim']

Set Instrument¶

The TOF calibration (offset, linear, and quadratic d-to-TOF terms) is what converts the default d-spacing window into a time window.

In [12]:

experiment.instrument.setup_twotheta_bank = 144.845
experiment.instrument.calib_d_to_tof_offset = 0.0
experiment.instrument.calib_d_to_tof_linear = 7476.91
experiment.instrument.calib_d_to_tof_quadratic = -1.54

experiment.instrument.setup_twotheta_bank = 144.845 experiment.instrument.calib_d_to_tof_offset = 0.0 experiment.instrument.calib_d_to_tof_linear = 7476.91 experiment.instrument.calib_d_to_tof_quadratic = -1.54

Set Peak Profile¶

In [13]:

experiment.peak.broad_gauss_sigma_0 = 3.0
experiment.peak.broad_gauss_sigma_1 = 40.0
experiment.peak.broad_gauss_sigma_2 = 2.0
experiment.peak.decay_beta_0 = 0.04221
experiment.peak.decay_beta_1 = 0.00946
experiment.peak.rise_alpha_0 = 0.0
experiment.peak.rise_alpha_1 = 0.5971

experiment.peak.broad_gauss_sigma_0 = 3.0 experiment.peak.broad_gauss_sigma_1 = 40.0 experiment.peak.broad_gauss_sigma_2 = 2.0 experiment.peak.decay_beta_0 = 0.04221 experiment.peak.decay_beta_1 = 0.00946 experiment.peak.rise_alpha_0 = 0.0 experiment.peak.rise_alpha_1 = 0.5971

Set Background¶

In [14]:

experiment.background.type = 'line-segment'
experiment.background.create(id='1', position=10000, intensity=500)
experiment.background.create(id='2', position=40000, intensity=500)

experiment.background.type = 'line-segment' experiment.background.create(id='1', position=10000, intensity=500) experiment.background.create(id='2', position=40000, intensity=500)

Background type for experiment 'sim' already set to

line-segment

Set Calculation Range¶

In [15]:

experiment.data_range.time_of_flight_min = 5000.0
experiment.data_range.time_of_flight_max = 15000.0
experiment.data_range.time_of_flight_inc = 2.0

experiment.data_range.time_of_flight_min = 5000.0 experiment.data_range.time_of_flight_max = 15000.0 experiment.data_range.time_of_flight_inc = 2.0

Set Linked Structures¶

In [16]:

experiment.linked_structures.create(structure_id='si', scale=10.0)

experiment.linked_structures.create(structure_id='si', scale=10.0)

🚀 Perform Calculation¶

Display Pattern¶

In [17]:

project.display.pattern(expt_name='sim')

project.display.pattern(expt_name='sim')

Loading plot…

In [18]:

project.display.pattern(expt_name='sim', x_min=5000, x_max=6000)

project.display.pattern(expt_name='sim', x_min=5000, x_max=6000)

Loading plot…

Inspect as Text¶

In [19]:

project.experiments['sim'].show_as_text()

project.experiments['sim'].show_as_text()

Experiment 🔬 'sim' as text

	Edi
1	data_sim
2
3	_experiment_type.sample_form powder
4	_experiment_type.beam_mode time-of-flight
5	_experiment_type.radiation_probe neutron
6	_experiment_type.scattering_type bragg
7
8	_diffrn.ambient_temperature ?
9	_diffrn.ambient_pressure ?
10	_diffrn.ambient_magnetic_field ?
11	_diffrn.ambient_electric_field ?
12
13	_calculator.type cryspy
14
15	_data_range.time_of_flight_min 5000.
16	_data_range.time_of_flight_max 15000.
17	_data_range.time_of_flight_inc 2.
18
19	_peak.rise_alpha_0 0.
20	_peak.rise_alpha_1 0.5971
21	_peak.decay_beta_0 0.04221
22	_peak.decay_beta_1 0.00946
23	_peak.broad_gauss_sigma_0 3.
24	_peak.broad_gauss_sigma_1 40.
25	_peak.broad_gauss_sigma_2 2.
26	_peak.broad_gauss_size_g 0.
27	_peak.broad_gauss_strain_g 0.
28	_peak.cutoff_fwhm 0.
29	_peak.type tof-jorgensen
30
31	_instrument.setup_twotheta_bank 144.845
32	_instrument.calib_d_to_tof_offset 0.
33	_instrument.calib_d_to_tof_linear 7476.91
34	_instrument.calib_d_to_tof_quadratic -1.54
35	_instrument.calib_d_to_tof_reciprocal 0.
36
37	_absorption.type none
38
39	loop_
40	_linked_structure.structure_id
41	_linked_structure.scale
42	si 10.
43
44	_background.type line-segment
45
46	loop_
47	_background.id
48	_background.position
49	_background.intensity
50	1 10000 500
51	2 40000 500
52
53	loop_
54	_refln.id
55	_refln.structure_id
56	_refln.d_spacing
57	_refln.sin_theta_over_lambda
58	_refln.index_h
59	_refln.index_k
60	_refln.index_l
61	_refln.f_calc
62	_refln.f_squared_calc
63	_refln.time_of_flight
64	1 si 1.92014846 0.26039653 2 2 0 3.20863212 10.29532007 14351.09932031
65	2 si 1.63750811 0.305342 3 1 1 2.24018272 5.01841861 12239.37137416
66	3 si 1.56779466 0.31891932 2 2 2 0. 0. 11718.47425195
67	4 si 1.35775 0.36825631 4 0 0 3.10167267 9.62037338 10148.9355855
68	5 si 1.24595685 0.40129801 3 3 1 2.16550644 4.68941815 9313.51652715
69	6 si 1.21440852 0.41172307 4 2 0 0. 0. 9077.75202306
70	7 si 1.10859823 0.45102002 4 2 2 2.99827871 8.98967524 8286.9965678
71	8 si 1.04519644 0.47837897 5 1 1 2.09331949 4.3819865 7813.15734337
72	9 si 1.04519644 0.47837897 3 3 3 2.09331949 4.3819865 7813.15734337
73	10 si 0.96007423 0.52079306 4 4 0 2.89833138 8.40032478 7176.96914365
74	...
75	15 si 0.82821974 0.60370452 5 3 3 1.95608441 3.82626623 6191.46806257
76	16 si 0.81875406 0.610684 6 2 2 0. 0. 6120.71803871
77	17 si 0.78389733 0.63783863 4 4 4 2.70832085 7.33500184 5860.18344831
78	18 si 0.76049211 0.65746901 5 5 1 1.89087853 3.5754216 5685.24043305
79	19 si 0.76049211 0.65746901 7 1 1 1.89087853 3.5754216 5685.24043305
80	20 si 0.75314419 0.6638835 6 4 0 0. 0. 5630.317808
81	21 si 0.7257479 0.68894446 6 4 2 2.61803924 6.85412944 5425.5406156
82	22 si 0.70705598 0.70715759 5 5 3 1.82784627 3.34102199 5285.8240047
83	23 si 0.70705598 0.70715759 7 3 1 1.82784627 3.34102199 5285.8240047
84	24 si 0.678875 0.73651261 8 0 0 2.53076715 6.40478236 5075.1775345

💾 Save Project¶

In [20]:

project.save_as(dir_path='projects/simulate-si-tof')

project.save_as(dir_path='projects/simulate-si-tof')

Saving project 📦 'si_simulation' to '../../../projects/simulate-si-tof'

├── 📄 project.edi

├── 📁 structures/

│   └── 📄 si.edi

├── 📁 experiments/

│   └── 📄 sim.edi

├── 📁 analysis/

│   └── 📄 analysis.edi

└── 📁 reports/

    └── 📄 si_simulation.html