You are here: start » gem

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision		Previous revision
gem [2011/05/27 14:44] – schneidergem [2020/03/06 09:12] (current) – external edit 127.0.0.1
Line 1: Line 1:
-====== Replacing Wien 2K ======+====== FLAIR/GEM - an Alternative to Wien 2K ======
  
-The purpose of this page is to solicit input/feedback from the students in Ph 575 on the use of Wien 2K as a teaching tool in Ph575. Please add/comment to the strength and weaknesses of Wien 2K and the add/comment on proposed features of the new system (flair/gem) described below. Please mark your edits with your initials (JD) but you don't have to.+Guenter's new [[http://www.physics.oregonstate.edu/~schneidg/ph575project-flair-gem/|Flair/Gem page]] with Si tutorial, basic instructions. 
 + 
 +The purpose of this page is to solicit input/feedback from the students in Ph 575 on the use of Wien 2K as a teaching tool in Ph575. Please add/comment on the strength and weaknesses of Wien 2K and add/comment on proposed features of the new system (flair/gem) described below. It would help to mark your edits with your name, but you don't have to. You can also email Guenter at Guenter.Schneider@physics.oregonstate.edu and Janet at tate@physics.oregonstate.edu.
  
 ==== Strengths of Wien 2K ==== ==== Strengths of Wien 2K ====
Line 24: Line 26:
     * web interface not always easy or intuitive (gs)     * web interface not always easy or intuitive (gs)
          * if the defaults don't work you need to consult a very extensive handbook which was not written for beginners (gs)          * if the defaults don't work you need to consult a very extensive handbook which was not written for beginners (gs)
-         * there is no //graded// access to the input parameters. You have to go through all of them every single time. A scheme //essential//, //intermediate//, //advanced//, and //expert// would allow focus on relevant parameters and expand as needed.(gs)+         * there is no //graded// access to the input parameters. You have to go through all of them every single time. A scheme like //essential//, //intermediate//, //advanced//, and //expert// would allow focus on relevant parameters and you could expand the number of parameters as needed.(gs)
          
     * not easy to figure out what is calculated besides the basics (band structure, DOS, Fermi energy) For example Wien 2K calculates the magnetic moment of a ferromagnetic material but you need to figure out yourself where you can find this number (gs)     * not easy to figure out what is calculated besides the basics (band structure, DOS, Fermi energy) For example Wien 2K calculates the magnetic moment of a ferromagnetic material but you need to figure out yourself where you can find this number (gs)
Line 36: Line 38:
 On top of //gem// we will build a web interface unless I hear from you that that is really not needed. A web interface (really a form based interface) will always be limited in its scope (or really expensive) but there is always //gem// the python layer to access more interesting data. On top of //gem// we will build a web interface unless I hear from you that that is really not needed. A web interface (really a form based interface) will always be limited in its scope (or really expensive) but there is always //gem// the python layer to access more interesting data.
          
 +
 +==== Current features of gem+flair not present in Wien 2K ====
  
          * all computers in Weniger 412 + 497 (currently >30) can run //flair+gem//. No more access problems during crunch time.          * all computers in Weniger 412 + 497 (currently >30) can run //flair+gem//. No more access problems during crunch time.
          * It is free and it can run on your Mac and Windows machines too.           * It is free and it can run on your Mac and Windows machines too. 
-         * //gem// has graphics (2D/3D) build in.+         * //gem// has graphics (2D/3D) built in.
          * No need to access all parameters of flair. You can concentrate on the important ones.           * No need to access all parameters of flair. You can concentrate on the important ones. 
  
 ==== Wishlist ===== ==== Wishlist =====
  
-This is your chance to shape future teaching!+This is your chance to shape future teaching! Please add here or email (see top of page for email addresses).
  
   * What features would you like to see?    * What features would you like to see? 
Line 53: Line 57:
   * Something you tried to do but couldn't?   * Something you tried to do but couldn't?
        * add yours ...        * add yours ...
 +
 +==== From the instructor's perspective (JT)====
 +I would like the students to learn to use a real research tool that will be useful to them as they pursue research in solid state physics as experimentalists (as most will become).  Obviously, as theorists, they will use this type of tool, too, but theorists will very quickly HAVE to go beyond the level presented in this course.
 +
 +There must be a reasonable compromise between frustration (a barrier right now) and a black box (no learning).
 +
 +Important things that should NOT be black-box:
 +  * learn to interpret a cif file (at least find the lattice positions, lattice parameters, and know what's important) and set up a structure from crystallographic information.  Distinguish between different origins (e.g. Si) 
 +  * Be able to monitor the convergence process  
 +  * Plot the density of states, partial density of states - same breakdown as in Wien (including interstitial)
 +  * Understand that the size of the atom radii matters, and be able to find out how many electrons are "lost" by particular choice of atom radii
 +  * Know the difference between core states and valence electron states
 +  * Understand that the density of k-points is important and how to choose so that accuracy is maximized and computation time is minimized.
 +  * Plot the band structure ("spaghetti diagram"), and be able to choose a k-path for the band structure plot (as in x-crysden)
 +
 +
 +Things that //should// be black-box, but //aren't// in Wien:
 +  * swapping the k-files for DoS and spaghetti should be automatic
 +  * fewer error messages
 +  * pointing and clicking through the scf is pointless
 +  * Having to find the Fermi energy and manually substitute it in one file is bad
 +
 +Capabilities of the new program
 +  * Be able to calculate magnetic moments (need a sub list here to see how automated this should be)
 +  * Be able to calculate optical absorption (need a sub list here to see how automated this should be)
 +  * Be able to plot electron density (need a sub list here to see how automated this should be)
 +  * Be able to plot Fermi surface (need a sub list here to see how automated this should be)
 +  * find total energy minimum, and hence optimize lattice constants
 +
 +
 +
  
  

Trace:

QR Code
QR Code gem (generated for current page)