[mcstas-users] Diffraction Pattern of Si
Andrew Wildes
wildes at ill.fr
Wed Nov 22 15:38:25 CET 2017
Hi all,
The Si.laz file looks like it’s been generated from the ICSD card. Running it through ICSD gives the following error:
***WARNING*** FD3-Ms with axes not at center! Lazy & xtal-3d will FAIL
This boils down to the choice of the origin in the definition of the unit cell. To get Lazy to work, the fractional coordinates for Si need to be changed to x = 0.125, y = 0.125, z = 0.125.
Someone please correct me if I’m wrong on this!
I believe that Si.laz was generated using a neutron wavelength of 1 A and a maximum twotheta of 150 degrees. I’ve run the modified card through Lazy via the ICSD database using the same reference as Si.laz (i.e. Toebbens et al) for the lattice parameters and the default UVW. I don’t know if anything else needs to be changed, but in the short term you can replace the information below the hashed lines with the following text:
1 1 1 9.18 18.35 3.1353 0.1017 25.43 1 1 1 910.1 2.3 -2.32 0.00 180.00 8 39.83
2 2 0 15.09 30.19 1.9200 0.2713 67.82 2 2 0 1000.0 3.2 -3.21 0.00 180.00 12 15.27
3 1 1 17.78 35.56 1.6374 0.3730 93.25 3 1 1 717.4 2.2 -2.24 0.00 180.00 24 11.26
2 2 2 18.60 37.20 1.5677 0.4069 101.73 2 2 2 0.0 0.0 0.00 0.00 0.00 8 10.37
4 0 0 21.61 43.22 1.3576 0.5425 135.64 4 0 0 241.3 3.1 -3.09 0.00 180.00 6 7.93
3 3 1 23.66 47.32 1.2458 0.6443 161.07 3 3 1 401.3 2.2 2.16 0.00 0.00 24 6.78
4 2 2 26.81 53.62 1.1085 0.8138 203.45 4 2 2 622.9 3.0 2.98 0.00 0.00 24 5.51
5 1 1 28.58 57.16 1.0451 0.9155 228.89 5 1 1 273.8 2.1 2.08 0.00 0.00 24 4.98
3 3 3 28.58 57.16 1.0451 0.9155 228.89 3 3 3 91.3 2.1 2.08 0.00 0.00 8 4.98
4 4 0 31.39 62.78 0.9600 1.0851 271.27 4 4 0 227.0 2.9 2.87 0.00 0.00 12 4.32
5 3 1 33.00 66.01 0.9179 1.1868 296.70 5 3 1 411.0 2.0 2.00 0.00 0.00 48 4.02
4 4 2 33.53 67.07 0.9051 1.2207 305.18 4 4 2 0.0 0.0 0.00 0.00 0.00 24 3.93
6 2 0 35.61 71.23 0.8586 1.3564 339.09 6 2 0 354.4 2.8 2.77 0.00 0.00 24 3.63
5 3 3 37.14 74.28 0.8281 1.4581 364.52 5 3 3 163.6 1.9 -1.93 0.00 180.00 24 3.44
6 2 2 37.64 75.29 0.8187 1.4920 373.00 6 2 2 0.0 0.0 0.00 0.00 0.00 24 3.39
4 4 4 39.63 79.27 0.7838 1.6276 406.91 4 4 4 96.6 2.7 -2.67 0.00 180.00 8 3.19
5 5 1 41.11 82.22 0.7604 1.7294 432.34 5 5 1 135.6 1.9 -1.86 0.00 180.00 24 3.07
7 1 1 41.11 82.22 0.7604 1.7294 432.34 7 1 1 135.6 1.9 1.86 0.00 0.00 24 3.07
6 4 2 43.55 87.10 0.7257 1.8989 474.73 6 4 2 490.5 2.6 -2.58 0.00 180.00 48 2.91
5 5 3 45.01 90.02 0.7070 2.0006 500.16 5 5 3 116.1 1.8 -1.80 0.00 180.00 24 2.83
7 3 1 45.01 90.02 0.7070 2.0006 500.16 7 3 1 232.2 1.8 -1.80 0.00 180.00 48 2.83
8 0 0 47.44 94.88 0.6788 2.1702 542.54 8 0 0 53.4 2.5 2.48 0.00 0.00 6 2.73
7 3 3 48.91 97.81 0.6634 2.2719 567.98 7 3 3 102.2 1.7 -1.73 0.00 180.00 24 2.68
6 4 4 49.40 98.80 0.6585 2.3058 576.45 6 4 4 0.0 0.0 0.00 0.00 0.00 24 2.67
6 6 0 51.38 102.75 0.6400 2.4415 610.36 6 6 0 95.7 2.4 -2.39 0.00 180.00 12 2.62
8 2 2 51.38 102.75 0.6400 2.4415 610.36 8 2 2 191.3 2.4 -2.39 0.00 180.00 24 2.62
7 5 1 52.88 105.76 0.6271 2.5432 635.79 7 5 1 184.8 1.7 -1.67 0.00 180.00 48 2.61
5 5 5 52.88 105.76 0.6271 2.5432 635.79 5 5 5 30.8 1.7 1.67 0.00 0.00 8 2.61
6 6 2 53.39 106.77 0.6229 2.5771 644.27 6 6 2 0.0 0.0 0.00 0.00 0.00 24 2.60
8 4 0 55.44 110.88 0.6072 2.7127 678.18 8 4 0 176.1 2.3 -2.31 0.00 180.00 24 2.60
7 5 3 57.02 114.03 0.5961 2.8145 703.61 7 5 3 172.0 1.6 1.61 0.00 0.00 48 2.61
9 1 1 57.02 114.03 0.5961 2.8145 703.61 9 1 1 86.0 1.6 -1.61 0.00 180.00 24 2.61
8 4 2 57.55 115.10 0.5925 2.8484 712.09 8 4 2 0.0 0.0 0.00 0.00 0.00 48 2.62
6 6 4 59.74 119.47 0.5789 2.9840 746.00 6 6 4 167.4 2.2 2.22 0.00 0.00 24 2.66
9 3 1 61.44 122.88 0.5693 3.0857 771.43 9 3 1 166.1 1.6 -1.55 0.00 180.00 48 2.71
8 4 4 64.44 128.88 0.5543 3.2553 813.82 8 4 4 166.6 2.1 2.14 0.00 0.00 24 2.85
9 3 3 66.36 132.73 0.5458 3.3570 839.25 9 3 3 84.6 1.5 1.50 0.00 0.00 24 2.97
7 7 1 66.36 132.73 0.5458 3.3570 839.25 7 7 1 84.6 1.5 1.50 0.00 0.00 24 2.97
7 5 5 66.36 132.73 0.5458 3.3570 839.25 7 5 5 84.6 1.5 1.50 0.00 0.00 24 2.97
10 2 0 69.88 139.75 0.5325 3.5265 881.64 10 2 0 179.3 2.1 -2.07 0.00 180.00 24 3.30
8 6 2 69.88 139.75 0.5325 3.5265 881.64 8 6 2 358.5 2.1 2.07 0.00 0.00 48 3.30
9 5 1 72.25 144.50 0.5250 3.6283 907.07 9 5 1 191.3 1.4 1.44 0.00 0.00 48 3.62
7 7 3 72.25 144.50 0.5250 3.6283 907.07 7 7 3 95.7 1.4 1.44 0.00 0.00 24 3.62
10 2 2 73.11 146.21 0.5226 3.6622 915.54 10 2 2 0.0 0.0 0.00 0.00 0.00 24 3.76
6 6 6 73.11 146.21 0.5226 3.6622 915.54 6 6 6 0.0 0.0 0.00 0.00 0.00 8 3.76
Cheers, Andrew (don’t add this bit in the file!)
> On 22 Nov 2017, at 15:12, Linda Udby <udby at nbi.dk> wrote:
>
> Hi Saed,
>
> you are right the 220 reflection has zero intensity in the Si.laz file as you can see here
> http://www.mcstas.org/download/components/data/Si.laz <http://www.mcstas.org/download/components/data/Si.laz>
>
> I believe that is not correct for the diamond structure of Si (F -d 3m)
>
> S_Si(hkl)=S_fcc(hkl)[1+exp(i pi /2)(h+k+l)]
> where S_fcc(hkl)=4b_Si for h,k,l all odd or even, else S_fcc(hkl)=0
>
> hence
>
> S_Si(220) = 2 * S_fcc(hkl)= 8 b_Si
>
> ( but S_Si(hkl) = 0 if [h+k+l=2(2n+1)] )
>
> A solution would be to generate your own reflection list (h,k,l, Intensity) from e.g. crystallografica and input that as datafile to the component where you have used Si.laz before. When you have generated a better reflection list for Si I'm sure the McStas developers would be happy if you contribute it to the next McStas distro :)
>
> Best wishes
> Linda
>
> On 11/22/2017 09:21 AM, 새드하셈 wrote:
>>
>> Hello everyone,
>> Here is Mr. Saed Almomani from KAERI, I'm working on conceptual design of HRPD for the Jordan Research & Training Reactor JRTR. I'm using McStas software to test and verify my design, and when I used the Si.laz sample in my code I found that some of reflection planes are not shown in the diffraction pattern such as (220) !! then I tried to use D2B HRPD code (built-in McStas) to test the Si.laz sample and the problem was the same " the 220 reflection plane was not shown" !! then I tried to use the Al.laz sample and I got a perfect diffraction pattern !
>> So what is the problem and why is that ? is there any error in the (Si.laz) predefined sample of McStas ? and what is the best way to solve this problem?
>>
>> Thank you in advance
>>
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
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>
> --
> ----------~oOo~----------
> Dr. Linda Udby
> Associate Professor
> X-ray and Neutron Science
> Niels Bohr Institute
> University of Copenhagen
> tel: +45 23 83 98 77
> webpage: www.e-neutrons.org <http://www.e-neutrons.org/>
> ----------~oOo~----------
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