- JOHACHIDOLITE - CaAlB₃O₇

Theoretical atomic positions and lattice parameters at experimental volum from AMCSD

Crystal Structure

Because of the translational symmetry all the calculations are performed in the primitive unit cell and not in the conventional unit cell. The following information regarding the structure is given with respect to this primitive unit cell, which sometimes can take an unintuitive shape.

Symmetry (experimental):

Space group:	67		Cmma
Lattice parameters (Å):	7.9670	11.7230		4.3718
Angles (°):	90	90		90

Symmetry (theoretical):

Space group:	67		Cmma
Lattice parameters (Å):	7.3343	7.3343		4.2299
Angles (°):	90	90		63.80

Cell contents:

Number of atoms:	24
Number of atom types:	4
Chemical composition:	0

Atomic positions (theoretical):

Ca:	0.5000	0.0000	0.0000
Al:	0.0000	0.0000	0.0000
Al:	0.2500	0.7500	0.5000
B:	0.1270	0.1270	0.4074
B:	0.2500	0.2500	0.4067
O:	0.1183	0.1183	0.7420
O:	0.2219	0.9325	0.2430
Ca:	0.0000	0.5000	0.0000
Al:	0.5000	0.5000	0.0000
B:	0.3730	0.3730	0.4074
O:	0.3817	0.3817	0.7420
O:	0.2781	0.5675	0.2430
B:	0.6270	0.6270	0.5926
B:	0.7500	0.7500	0.5933
O:	0.6183	0.6183	0.2580
O:	0.4325	0.7219	0.7570
B:	0.8730	0.8730	0.5926
O:	0.8817	0.8817	0.2580
O:	0.0675	0.7781	0.7570
Al:	0.7500	0.2500	0.5000
O:	0.7781	0.0675	0.7570
O:	0.7219	0.4325	0.7570
O:	0.5675	0.2781	0.2430
O:	0.9325	0.2219	0.2430

Atom type

We have listed here the reduced coordinates of all the atoms in the primitive unit cell.
It is enough to know only the position of the atoms from the assymetrical unit cell and then use the symmetry to build the whole crystal structure.

Visualization of the crystal structure:

You can define the size of the supercell to be displayed in the jmol panel as integer translations along the three crystallographic axis.
Please note that the structure is represented using the primitive cell, and not the conventional one.

Powder Raman

Powder Raman spectrum

The intensity of the Raman peaks is computed within the density-functional perturbation theory. The intensity depends on the temperature (for now fixed at 300K), frequency of the input laser (for now fixed at 21834 cm^-1, frequency of the phonon mode and the Raman tensor. The Raman tensor represents the derivative of the dielectric tensor during the atomic displacement that corresponds to the phonon vibration. The Raman tensor is related to the polarizability of a specific phonon mode.

Choose the polarization of the lasers.

I ∥

I ⊥

I Total

Horizontal:

Xmin:
Xmax:

Vertical:

Ymin:
Ymax:

Data about the phonon modes

Frequency of the transverse (TO) and longitudinal (LO) phonon modes in the zone-center. The longitudinal modes are computed along the three cartesian directions. You can visualize the atomic displacement pattern corresponding to each phonon by clicking on the appropriate cell in the table below.

1	B2g	-266	-266	-266	-266
2	B3g	-180	-180	-180	-180
3	B2u	-142	-142	-134	-142
4	Ac	0	0	0	0
5	Ac	0	0	0	0
6	Ac	0	0	0	0
7	B3u	28	40	28	28
8	B1u	103	103	103	112
9	B3g	139	139	139	139
10	Au	140	140	140	140
11	B2u	152	152	156	152
12	B3u	156	158	189	156
13	B1g	189	189	206	189	1.400e+52 0.0	1.925e+52 0.0	3.325e+52 0.0
14	B1u	206	206	208	208
15	B2g	208	208	213	216
16	B1u	216	216	216	217
17	B3u	218	220	218	218
18	B2u	221	221	222	221
19	Au	254	254	254	254
20	B2g	282	282	282	282
21	B1g	292	292	292	292
22	Ag	310	310	310	310	1.437e+54 0.5	7.514e+53 0.2	2.188e+54 0.7
23	B3u	312	313	312	312
24	B3g	348	348	348	348
25	Ag	357	357	357	357	2.336e+56 73.5	8.405e+55 26.5	3.176e+56 100.0
26	Au	364	364	364	364
27	B2g	381	381	381	381
28	B1u	385	385	385	385
29	B1g	418	418	418	418
30	B2u	431	431	434	431
31	B3u	434	434	445	434
32	Au	450	450	450	450
33	B3u	483	483	483	483
34	B1u	485	485	485	485
35	B1g	507	507	507	507
36	B1u	517	517	517	521
37	Ag	521	521	521	529	1.970e+53 0.1	9.886e+52 0.0	2.959e+53 0.1
38	B2u	535	535	538	535
39	B1u	555	555	555	566
40	B3g	566	566	566	567
41	Au	582	582	582	582
42	Ag	600	600	600	600
43	B2g	601	601	601	601
44	B3u	615	616	615	615
45	B2u	623	623	624	623
46	B1u	686	686	686	693
47	B3g	693	693	693	697
48	Au	741	741	741	741
49	B2u	745	745	757	745
50	B1u	757	757	763	757
51	Ag	780	780	780	780	7.611e+52 0.0	7.597e+52 0.0	1.521e+53 0.0
52	B2u	804	804	809	804
53	B3g	810	810	810	810
54	B3u	833	833	833	833
55	B1g	840	840	840	840
56	B2g	874	874	874	874
57	Ag	909	909	909	909	9.439e+54 3.0	3.064e+54 1.0	1.250e+55 3.9
58	B3u	940	944	940	940
59	B2g	947	947	947	947
60	B3g	968	968	968	968
61	B1g	982	982	982	982
62	B2u	995	995	1001	995
63	B1u	1001	1001	1004	1006
64	Au	1057	1057	1057	1057
65	B3g	1082	1082	1082	1082
66	B2u	1084	1084	1084	1084
67	Ag	1086	1086	1086	1086	3.407e+53 0.1	4.269e+53 0.1	7.677e+53 0.2
68	B1u	1106	1106	1106	1124
69	B1u	1141	1141	1141	1143
70	Ag	1221	1221	1221	1221	1.698e+51 0.0	1.904e+51 0.0	3.603e+51 0.0
71	B3g	1547	1547	1547	1547
72	B2u	1548	1548	1549	1548

No.

Char.

ω TO

ω LOx

ω LOy

ω LOz

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I ⊥