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papers [2013/05/17 09:45] – tatepapers [2019/03/04 14:04] – janettate
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-====== Paper/poster assignment (Midterm 2) ======+====== DFT project ======
  
-One of the goals of the course is to become familiar with modern computational software that allows one to solve difficult problems. You will use the software package Wien 2k or Flair/Gem to calculate the band structure of a semiconductor, metal, or insulator.  Decide on an interesting system (talk to me and others about what is feasible). You always start by reproducing the work of others, and then go on to explore by yourself. You will calculate (at minimum for a passing grade) the dispersion relation and the total and partial densities of states of an interesting material. You will also calculate at least one other property – electron density, optical properties etc., for a B or higher grade. The difficulty of the project will be taken into account in assigning the grade. More information about the programs is under the Wien 2k link and the Flair/Gem link.+One of the goals of the course is to become familiar with modern computational software that solve difficult problems in solid state physics. You will use the software package OpenMX to calculate the band structure of a semiconductor, metal, or insulator. You can complement your own calculations by downloading band structures from an open source project called aflow. Decide on an interesting system (talk to the instructor and others about what is feasible). You always start by reproducing the work of others, and then go on to explore by yourself. You will calculate (at minimum for a passing grade) the dispersion relation and the total and partial densities of states of an interesting material. You will also calculate at least one other property – electron density, optical properties, spin polarization etc., for a B or higher grade. The difficulty of the project will be taken into account in assigning the grade.
  
-Write a **paper** that describes your findings.  It should should explain (i) what you have learned about band structure calculations during this process, and (ii) explain what is topical and interesting about your material in somewhat greater detail than you poster. Include references about both sub-parts. This paper should distill the knowledge you have gained about electronic structure, and be well-constructed to be very helpful to incoming PH575 students. It should show evidence of your scientific curiosity, and your ability to explain the essential concepts.  +===== Poster assignment ===== 
 +Summarize your results as a poster to be shown during class (date will be posted on the main calendar of the course). This is a conference of your peers, and may also be attended by interested parties such as former and prospective PH575 students, and faculty. OSU Student Media Services, located in the Valley Library, print posters for free if it is a class assignment. A typical poster size is 3 feet wide, 3.5 - 4 feet tall. Text and diagrams should explain your calculations, and provide other information about your material. During the poster session, you'll stay with your poster for 50% of the time, and circulate around other posters for 50% of the time.
  
-Summarize your results as a **poster** for the group to be shown in the hour reserved for MT2.  This is a conference of your peers, and may also be attended by interested parties such as former and prospective PH575 students, and faculty.  You should not go to great expense to generate the posters; 8.5” by 11” sheets pasted to thin poster board will be fine. The total size is limited to about half the size of a whiteboard in WGR 304. Text and diagrams should explain your calculations, and provide supplementary information about your material. In the poster session, half the class will remain with the poster for the first half while the other half circulate; roles are swapped for the second half.+===== Paper assignment ===== 
 + 
 +After the poster session, you will write a paper that describes your findings. The feedback you get from the poster should help you write a better paper. 
 + 
 +General things I look for when grading the paper: 
 + 
 +      * the paper distills the knowledge you have gained about electronic structure, 
 +      * the paper would be helpful to an audience of incoming PH575 student (the instructor will put himself in the shoes of typical PH575 students when deciding if the paper is well written). 
 +      * the paper shows evidence of your scientific curiosity, and your ability to explain essential concepts. 
 + 
 + 
 +Specific points I look for: 
 + 
 +      * Good discussion of what your calculations show. 
 +      * Figures are easy to read (font size is big enough, axes are labelled, captions are sufficient to interpret the figure) 
 +      * The paper includes real-world connections such as applications of the material, or the reason for academic interest in the material. 
 +      * The paper cites a number of appropriate references from academic literature. 
 + 
 +Typical papers in the past have been about 8 pages including figures and references. Please use 12 point Times or 11 point Arial. Please use 1.5 x line spacing and 1.25” margins. These are standard choices for an academic manuscript and make grading easier. Color printing can make a huge difference for interpreting crystal structures, partial DoS etc. 
 + 
 +If you have questions, please ask! I will almost always email the whole class with my answer, or post the answers here under FAQ.
  
-If you have questions, please ask!  I will almost always email the whole class with my answer, or post the answers here under FAQ. 
  
 ====== FAQ ====== ====== FAQ ======
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 Here are some ideas that might stimulate your creativity Here are some ideas that might stimulate your creativity
  
-  * explore another option within Wien of Flair+  * explore another option within OpenMX
   * pose a question that could be explored using this new tool   * pose a question that could be explored using this new tool
   * study a family of materials   * study a family of materials
-  * go beyond the standard "default clicks" in Wien to explore something you found interesting+  * go beyond the standard "default clicks" to explore something you found interesting
   * choose a more challenging material (not always recommended because this is often an all-or-nothing proposition).   * choose a more challenging material (not always recommended because this is often an all-or-nothing proposition).
  
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 Why a poster as well as a paper? It's so that you can share your work with the other students and learn something from them, too.  Science is about communicating ideas and results, so you need to practice that.  So come up with something interesting to tell your peers. Why a poster as well as a paper? It's so that you can share your work with the other students and learn something from them, too.  Science is about communicating ideas and results, so you need to practice that.  So come up with something interesting to tell your peers.
    
-=== Cautions ===+=== Pitfalls ===
 Don't write a technical manual (“go to this menu, and click this button”). Don't write a technical manual (“go to this menu, and click this button”).
  
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 ===== Questions from class re the project ===== ===== Questions from class re the project =====
 +Do students from previous years have useful advice for me?
 +
 +Yes! Here is the advice from previous years.
 +Q. What is a CIF file
 +
 +A. The Crystallographic Information File (CIF) is the standard for crystallographic data exchange prescribed by the International Union of Crystallography. It was described in a paper in Acta Cryst. (1991). A47, 655–685 by S. R. Hall, F. H. Allen and I. D. Brown.
 +
 +Here is some of the text from a CIF file describing anatase TiO2:
 +
 +''_atom_site_label
 +_atom_site_type_symbol
 +_atom_site_fract_x
 +_atom_site_fract_y
 +_atom_site_fract_z
 +_atom_site_occupancy
 +_atom_site_U_iso_or_equiv
 +Ti1 Ti+4 0 0 0 1 0.0
 +O1 O-2 0.2821 0.2821 0 1 0.0''
 +
 +Translating the above code into english: “There is a Ti atom at (x,y,z) = (0,0,0) and an O atom at (0.2821a, 0.2821b, 0), where a and b are unit cell dimensions.
 +
 +It is helpful to drag a CIF file into the OpenMX Viewer (a browser based application) to see the crystal structure. You may wish to export the crystal structure as an .xyz file so that you have the actual atomic coordinates.
 +Can I try grading someone's paper from a previous year?
 +
 Q.  How do I know my band structure is right?  Q.  How do I know my band structure is right? 
  
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 Q.  My material has 80 atoms per unit cell - that OK? Q.  My material has 80 atoms per unit cell - that OK?
  
-A.  80 atoms is too big for our system, but there may be some symmetry that allows a smaller cell to be used and Wien will find it.  So try it and see.  If it's too big, you'll use all the memory and tie up the system so no one can use it.  Not good!  +A.  80 atoms is too big for our system.
  
 Q. Can I study doping, (eg B-doped Si) or solid solutions like ZnS_(1-y)Se_y? Q. Can I study doping, (eg B-doped Si) or solid solutions like ZnS_(1-y)Se_y?
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 Q. Can I study graphene? Q. Can I study graphene?
  
-A.  The 2-d nature of graphene requires special symmetry that is too difficult for a beginning project in Wien.  Graphite is a better choice.  (You might be able to use Flair for graphene, but you must do a 3-d structure in addition to graphene if you go this route.)+A.  We've looked at this material in class, so if you really want to do this, look for a new, related 2D material or try some advanced options.
  
 Q. Can I study conductivity as a function of temperature? Q. Can I study conductivity as a function of temperature?
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 A.  There is an option to include spin polarization, which should allow you to determine whether a material is magnetic or not in its ground state.   A.  There is an option to include spin polarization, which should allow you to determine whether a material is magnetic or not in its ground state.  
- 
-====== 2013 Papers ====== 
- 
-TBA 
  

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