[RMCProfile-users] RMCPROFILE

Henrik Mauroy hmauroy at gmail.com
Fri May 9 14:14:05 BST 2014


Dear Benoit.
Could you please inform the email list how things go? Use an informative 
topic for the email next time;)
I would also like to work on my x-ray PDFs and/or include them when 
running neutron data obtained at GEM. So far I haven't had time yet. I'm 
sure several others would also like to hear your comments, and about 
your eventual success with your data.

Best,
Henrik

On 09.05.2014 13:37, Benoit Baptiste wrote:
> Dear Helen,
>
> Thank you very much for these very useful informations.
> I will try as soon as possible.
> I'm also happy to read that a new version is coming soon !
>
> sincerely,
>
> B. Baptiste
>
>
> helen.playford at stfc.ac.uk a ?crit?:
>
>> Dear Benoit,
>>
>> Thanks for your email. Here is some more information about using 
>> RMCProfile with X-ray data. I am working on an example to show how it 
>> works for the next release of the program (coming soon!) which will 
>> hopefully clear things up further.
>>
>> To fit an X-ray F(Q) you can use the XRAY_RECIPROCAL_SPACE_DATA 
>> keyword. The datafile that you use must contain the X-ray form 
>> factors and the data itself must be convolved with the box size. 
>> There is a program called xray_to_rmc included with RMCProfile that 
>> will take data in the 'normal' rmc format, which is a two column 
>> ascii starting with the number of data points, like so:
>>
>> 1200
>> #title line
>> x1 y1
>> x2 y2
>> .    .
>> .    .
>> xn yn
>>
>> and make a correctly formatted X-ray data file.
>>
>> Currently an X-ray PDF can be treated like a neutron PDF but with 
>> different weightings. This is obviously an approximation and it's 
>> important to fit the F(Q) and Bragg (if applicable) as well.
>>
>> So for an X-ray PDF you use the NEUTRON_REAL_SPACE_DATA keyword, and 
>> supply a subordinate keyword NEUTRON_COEFFICIENTS which defines the 
>> weightings. These you calculate in the same way as for neutrons but 
>> replace the scattering length, b, with atomic number of the element 
>> in question.
>>
>> I hope this answers your query but please do get in touch if not or 
>> if you have further questions.
>>
>> Best wishes,
>> Helen
>>
>>
>>
>> From: rmcprofile-users 
>> [mailto:rmcprofile-users-bounces at rmcprofile.org] On Behalf Of Benoit 
>> Baptiste
>> Sent: 05 May 2014 08:52
>> To: rmcprofile-users at rmcprofile.org
>> Subject: Re: [RMCProfile-users] RMCPROFILE
>>
>> Dear Helen,
>>
>> I'm also working with x-ray PDFs (obtained with pdfgetx3 from Ag 
>> source measurements) and I've read there is maybe a way to use it in 
>> rmc profile. If it's possible, could you please give me more details 
>> about that ? I didn't find anything in the manual...
>>
>> Thanks in advance,
>>
>> Benoît Baptiste
>>
>>
>>
>> -- 
>>
>> Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie
>>
>> Plateforme de diffraction des rayons X
>>
>> 4 Place Jussieu - case courrier 115
>>
>> 75005 Paris
>>
>>
>> Le 28/04/2014 13:22, 
>> helen.playford at stfc.ac.uk<mailto:helen.playford at stfc.ac.uk> a écrit :
>> Dear H.Wu,
>>
>> Thank you for your email.
>>
>> The keyword XRAY_RECIPROCAL_SPACE_DATA should work (but requires the 
>> data to be in a very specific format, which we are working on an 
>> example for), but at the present time the keyword 
>> XRAY_REAL_SPACE_DATA is not implemented as there are questions over 
>> the accuracy of the Fourier transform. There are ways around this if 
>> you need to work with X-ray PDFs, which I can explain in more detail 
>> if necessary. Keywords with X_ at the start are not implemented.
>>
>> I am a little confused by your second paragraph. Do you have data 
>> from SiO2? In SiO2 each Si is coordinated to four, not five O atoms. 
>> The neighbour list file you show is telling you that some atoms do 
>> not have the expected number of neighbours. If you were trying to run 
>> with the SiO2 polyhedral restraint this would have caused the errors. 
>> How did you generate the second file? It would not have produced 
>> errors as each Si atom has 4 neighbours, but it's important that the 
>> connectivity is correct (i.e. that Si atom #1 is really connected to 
>> O atoms #65, 74, 79 and 85).
>>
>> Please let me know if you would like further help working with X-ray 
>> data, or if you have any other questions.
>>
>> Best wishes,
>> Helen
>>
>> From: rmcprofile-users 
>> [mailto:rmcprofile-users-bounces at rmcprofile.org] On Behalf Of ????
>> Sent: 22 April 2014 08:07
>> To: rmcprofile-users
>> Subject: [RMCProfile-users] RMCPROFILE
>>
>> Dear author ,
>>
>>       I 'm working with local atomic arrangement in disorder 
>> materials. When I study the RMCProfile software, I have some 
>> questions so need your help.
>>
>>       In the SF6 example, I can get better results after studying the 
>> manual. But for the rmcsf6.dat file, I have some questions on the 
>> keyword of "NEUTRON_REAL(or RECIPROCAL)_SPACE_DATA". If I have X-ray 
>> diffraction data, I will modify "NEUTRON" to "XRAY", but there will 
>> be some errors; but if I modify  "NEUTRON" to "X", then it will 
>> success, but there is no important "rmcsf6_PDF1.csv" and 
>> "rmcsf6_SQ1.csv" files in the makefiles. I don't know the reason.
>>
>>        Another question is restraint files. In the SF6 example, a S 
>> atom is adjacent with six O atoms and a O atom is adjacent with one S 
>> atom, because SF6 is unlinked octahedral material. When I research 
>> SiO2, SiO2 is linked tetrahedral material, so there exists boundary 
>> problem. In principle, a Si atom is adjacent with five O atoms and a 
>> O atom is adjacent with two Si atom. But when I use 
>> neighbour_list.exe to create restraint files, SiO2.sio is:
>>           64
>>      1     1      65
>>      2     2      66    80
>>      3     2      67    73
>>      4     2      68    79
>>      5     4      67    69    76    78
>>      6     4      65    73    79    80
>>      7     4      66    71    72    77
>>      8     4      68    70    74    75
>>      9     1      81
>>     10     4      69    74    82    96
>>     11     2      83    89
>>     12     2      84    95
>>     13     4      83    85    92    94
>>     14     4      81    89    95    96
>>     15     4      82    87    88    93
>>     16     4      84    86    90    91
>>     17     1      97
>>     18     2      98   112
>>     19     4      71    75    99   105
>>     20     2     100   111
>>     21     4      99   101   108   110
>>     22     4      97   105   111   112
>>     23     4      98   103   104   109
>>     24     4     100   102   106   107
>>     25     2      70   113
>>     26     4     101   106   114   128
>>     27     4      87    91   115   121
>>     28     2     116   127
>>     29     4     115   117   124   126
>>     30     4     113   121   127   128
>>     31     4     114   119   120   125
>>
>> But there is error when I run the RMCProfile. I artificially change 
>> SiO2.sio file to SF6-like restraint files, there is no error. I don't 
>> know the reasons.This is modified file:
>>           64
>>      1     4      65    74    79    85
>>      2     4      66    80    87    92
>>      3     4      67    73    78    86
>>      4     4      68    79    81    91
>>      5     4      67    69    76    78
>>      6     4      65    73    79    80
>>      7     4      66    71    72    77
>>      8     4      68    70    74    75
>>      9     4      81    88    93    99
>>     10     4      69    74    82    96
>>     11     4      83    89    98    116
>>     12     4      84    95    97    102
>>     13     4      83    85    92    94
>>     14     4      81    89    95    96
>>     15     4      82    87    88    93
>>     16     4      84    86    90    91
>>     17     4      97    99   105   116
>>     18     4      98   112   128   134
>>     19     4      71    75    99   105
>>     20     4     100   111   147   158
>>     21     4      99   101   108   110
>>     22     4      97   105   111   112
>>     23     4      98   103   104   109
>>     24     4     100   102   106   107
>>     25     4      70   113   139   178
>>     26     4     101   106   114   128
>>     27     4      87    91   115   121
>>     28     4     116   127   178   175
>>     29     4     115   117   124   126
>>     30     4     113   121   127   128
>>     31     4     114   119   120   125
>>
>> I know my expression have some questions, so I'm very sorry and hope 
>> you forgive me. Thank you very much!
>>
>> Best wish!
>>
>> H.Wu
>>
>>
>> -- 
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>>
>>
>>
>>
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