Last Modified 17 December 1999

The ``Static'' Tight-Binding Program: Example VI -- Output


If you've followed the steps on the setup page, your working directory should now look something like this:

$ ls -l
total 56
-rw-r--r--   2 mehl     users       15165 May 29 14:49 SKIN
-r--r--r--   2 mehl     users       24800 May 29 14:36 bcct.r24
-r--r--r--  11 mehl     1000         3369 Oct 23  1996 spcgrp
-r--r--r--   3 mehl     users        7131 May 28 15:46 w_par

Now run the static code in this directory. You'll get something like this:

$ static > output
$ ls -l
total 172
-rw-r-----   1 mehl     users        1638 May 29 16:15 SKENG
-rw-r--r--   2 mehl     users       15165 May 29 14:49 SKIN
-rw-r-----   1 mehl     users       63523 May 29 16:15 SKOUT
-r--r--r--   2 mehl     users       24800 May 29 14:36 bcct.r24
-rw-r-----   1 mehl     users       45270 May 29 16:15 output
-r--r--r--  11 mehl     1000         3369 Oct 23  1996 spcgrp
-r--r--r--   3 mehl     users        7131 May 28 15:46 w_par

As usual, we are most interested in the SKENG file:

c/a= 0.7928932188134  106.495045     .245515525     .035466285
c/a= 0.8343145750507  106.495045     .244665658     .026260127
c/a= 0.8757359312880  106.495045     .253653365     .015822141
c/a= 0.9171572875253  106.495045     .255887240     .007555561
c/a= 0.9585786437626  106.495045     .253761306     .002611486
c/a= 1.0000000000000  106.495045     .255663237     .000939437
c/a= 1.0414213562373  106.495045     .254489612     .002335352
c/a= 1.0828427124746  106.495045     .254727139     .005958762
c/a= 1.1242640687119  106.495045     .252026533     .011015765
c/a= 1.1656854249492  106.495045     .250194159     .016737165
c/a= 1.2071067811865  106.495045     .245580676     .022291406
c/a= 1.2485281374238  106.495045     .236603350     .027058916
c/a= 1.2899494936611  106.495045     .226966915     .031109964
c/a= 1.3313708498984  106.495045     .218978485     .033770778
c/a= 1.3727922061357  106.495045     .212698346     .035720557
c/a= 1.4142135623730  106.495045     .207708680     .036512289
c/a= 1.4556349186104  106.495045     .210408710     .035991657
c/a= 1.4970562748477  106.495045     .215684921     .034711389
c/a= 1.5384776310850  106.495045     .222271538     .033482626
c/a= 1.5798989873223  106.495045     .229530921     .032463211
c/a= 1.6213203435596  106.495045     .237794002     .032134603
c/a= 1.6627416997969  106.495045     .246875415     .032635958
c/a= 1.7041630560342  106.495045     .251939187     .033555519
c/a= 1.7455844122715  106.495045     .254599466     .035012487
c/a= 1.7870057685088  106.495045     .258550490     .037193150
c/a= 1.8284271247461  106.495045     .261382249     .040211144

Plotting this with the gnuplot script bain.gnu produces the following graph:

Bain Path of W a constant volume

This tells us that the bcc phase is stable at least against elastic distortions along the <001> direction; that the fcc phase is unstable with respect to the same type of strain, a common result for bcc transition metals; and that there is a possibly metastable bct phase near c/a = 1.6. I'll leave the question of the true stability of this structure as an exercise for the reader.


Return to the setup page.

Look at other examples.

Get other parameters from the Tight-binding periodic table.


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