prcantos
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Joined: 17 Apr 2012
Posts: 243
Location: Granada (Spain)
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Posted: Mar 05, 2015 06:06 Post subject: Re: Classification of crystallographic forms - any references? |
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Maybe I have found an answer to one of my previous questions: why are we using some dashed-lines matching symmetry elements which don't belong to the consider symmetry group? If they don't belong to the group they wouldn't be used to classify the forms.
The answer is related to 'Wyckoff positions' and 'crystallographic orbits'. These are concepts that appear in the study of space groups and can be transferred to point groups.
I haven't studied space groups before, but I am doing it now. I will tell you what I learn.
_________________ Pablo Rodríguez Cantos
Λίθον˛ον απεδοκίμασαν˛οι οικοδομουντες |
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prcantos
Site Admin
Joined: 17 Apr 2012
Posts: 243
Location: Granada (Spain)
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Posted: Mar 06, 2015 11:11 Post subject: Re: Classification of crystallographic forms - any references? |
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Meanwhile I add a new example of the matricial calculations of the forms for the group G=4/m, with the same notation and procedures. The columns in the matrix A are the images of (h,k,l) by identity, the 4-fold Z-axis rotation ρ and the XY-mirror symmetry σ.
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The matrix A resumes the symmetry of the group G=4/m. |
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6741 Time(s) |
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Discussion and resultant forms. Obviously the prism is an open form (without bases). |
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6702 Time(s) |
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Representation of the forms in the (h,k,l)-triangle. |
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6693 Time(s) |
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_________________ Pablo Rodríguez Cantos
Λίθον˛ον απεδοκίμασαν˛οι οικοδομουντες |
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