Control FermiSurfer

Launch

For Linux

You can launch generated executable as follows:

$ ./fermisurfer mgb2_vfz.fs

You need a space between the command and input-file name. (The sample input file mgb2_vfz.fs contains z element of the Fermi velocity in MgB2.)

For Windows

Click mouse right button on the input file. Choose “Open With ...” menu, then choose fermisurfer.exe.

After that, fermisurfer runs as the same whether you use Linux or Windows. The information from the input file is printed.

########################################
##                                    ##
##  Welocome to FermiSurfer ver. 1.8  ##
##                                    ##
########################################

  Number of threads : 4

  Initialize variables ...


  ##  Brillouin zone informations  ###########

    k point grid : 40 40 36
    k point grid starts from Gamma.
    # of bands : 3
    bvec 1 : 1.000000 0.577350 -0.000000
    bvec 2 : 0.000000 1.154701 0.000000
    bvec 3 : 0.000000 -0.000000 0.872065

  ##  Max. and Min. of each bands  #######################

    Band   Eig_Min.      Eig_Max      Mat_Min      Mat_Max
    1     -0.428153     0.056262     -24.048639     24.048639 (1)
    2     -0.289572     0.121181     -23.320309     23.320309 (1)
    3     -0.133566     0.497620     -43.651634     43.651634 (1)

  ##  First Brillouin zone mode  #######

    band   # of patchs
    1       8824  (2)
    2       29354 (2)
    3       28293 (2)


  ##  Full color scale mode #############

    Max. value : 22.283419  (3)
    Min. value : -22.251053 (3)

    band   # of nodeline
    1       632  (4)
    2       1524 (4)
    3       2268 (4)
    band   # of Fermi-line
    1       100
    2       736
    3       0

  ##  How to handle  ###################

              mouse drag : Rotate objects
              mousewheel : Resize objects
               cursorkey : Move objects
      mouse right button : Menu
  1. The maximum/minimum value of energies and matrix elements in each bands.
  2. The number of patches (planes that makes Fermi surfaces) in each bands.
  3. The maximum and the minimum of matrix elements on Fermi surface. These correspond to the red and the blue; in this case, the matrix element is -22.283419 in the blue region, and that is 22.283419 in the red region. [(1) is Max./Min. in whole Brillouin zone.]
  4. The number of node lines in each band.

Then, Operations are printed, and Fermi surfaces are drawn (Fig. 2).

_images/start.png

Main view.

The following operations are available:

  • Rotation of objects with mouse drag
  • Expand and shrink with mouse wheel
  • Window re-sizing
  • Moving objects with cursor keys
  • Opening the menu with mouse right button

Here, I will explain all menus.

Band

It makes each band enable/disable (Fig. 3).

_images/band.png

You make each band enable/disable with “Band” menu.

Background color

The background color is toggled between black and white; the edge of the Brillouin Zone is also toggled between white and black (Fig. 4).

_images/background.png

The background color is toggled with “Background color” menu.

Brillouin zone

You choose Brillouin-zone type as follows (Fig. 5):

First Brillouin Zone
The region surrounded by Bragg’s planes the nearest to {\rm \Gamma} point.
Primitive Brillouin Zone
A hexahedron whose corner is the reciprocal lattice point.
_images/brillouinzone.png

You can change the type of the Brillouin zone with “Brillouin zone” menu.

Color bar

The color bar becomes enable/disable (Fig. 6).

_images/colorbar.png

Toggling the color bar with “Color bar On/Off” menu.

Color scale mode

It turns color pattern on Fermi surfaces (Fig. 7).

Auto(default)
It makes blue as the minimum on Fermi surfaces and red as the maximum on them.
Manual
You can set manually (from standard input) values corresponding to blue and red.
Unicolor
Fermi surfaces of each band are depicted with uni-color without relation to the matrix element.
Periodic
It makes periodic color plot enable. When the matrix element varies as 0 \rightarrow \pi/ 3 \rightarrow 2\pi/ 3 \rightarrow \pi \rightarrow 4\pi/ 3 \rightarrow 5\pi/3 \rightarrow 2\pi, the color varies as red \rightarrow yellow \rightarrow green \rightarrow cyan \rightarrow blue \rightarrow magenta \rightarrow red.
Fermi velocity (Auto)
Compute the Fermi velocity {\bf v}_{\rm F} = \nabla_k \varepsilon_k with the numerical differentiation of the energy, and plot the absolute value of that. The color scale spans from the minimum and the maximum of |{\bf v}_{\rm F}| on the Fermi surface.
Fermi velocity (Manual)
Compute the Fermi velocity {\bf v}_{\rm F} = \nabla_k \varepsilon_k with the numerical differentiation of the energy, and plot the absolute value of that. The range of color scale can be specified manually from the terminal.
Gray scale (Manual), Gray scale (Auto)
Plot with gray scale.
_images/colorscale.png

“Color scale mode” menu.

Equator

We can draw the line where {\bf v}_{\rm F} \cdot {\bf k} = 0 for a vector {\bf k} (equator). See fig. 8

Equator
Toggle the equator.
Modify equator

We specify the {\bf k} vector. Please type a vector (fractional coordinate) at the prompt

New Miller index :
_images/equator.png

Display the equator with the “Equator” menu.

Interpolation

Smooth the Fermi surface with the interpolation (Fig. 9). Please type the number of interpolation points at the prompt

New interpolation ratio :

The time for the plot increases with the interpolation ratio.

_images/interpolate.png

Modify the number of interpolation points from 1 to 4 with “Interpolate” menu.

Lighting

We can choose the lighted side of the Fermi surface (Fig. 10).

Both side
Light both sides.
Unoccupied side
Light unoccupied side.
Occupied side
Light the occupied side.
_images/light.png

Change the lighted side by using the “Lighting” menu.

Line width

Modify the width of the Brillouin-zone boundary, the nodal line, etc.

Mouse Drag

It turns the event of the mouse-left-drag.

Rotate(default)
Rotate the figure along the mouse drag.
Scale
Expand/shrink the figure in upward/downward drag.
Translate
Translate the figure along the mouse drag.

Nodal line

The line on which the matrix element becomes 0 (we call it nodal line) becomes enable/disable (Fig. 11).

_images/nodeline.png

Toggling the node line with “Nodal line” menu.

Section

Display a 2D plot of the Fermi surface (line) on an arbitrary section of the Brillouin zone (Fig. 12).

Section
Toggle the 2D plot of the Fermi surface (line).
Modify Section

Specify the section. Please type the normal vector (fractional coordinate) at the prompt

New Miller index :

The section crosses the head of the normal vector.

Modify Section (across Gamma)

Specify the section. Please type the normal vector (fractional coordinate) at the prompt

New Miller index :

The section crosses \Gamma point.

_images/section.png

Display 2D plot of the Fermi surface (line) with “Section” menu.

Shift Fermi energy

It shifts the Fermi energy (= 0 in default) to arbitrary value. When you use this menu, first, it displays minimum and maximum energy in the input file and the current Fermi energy;

Min  Max  E_F
-0.428153 0.497620 0.000000
Fermi energy shift :

Then, you should type the new Fermi energy; finally, the new Fermi surfaces are depicted (Fig. 13).

_images/shift.png

The Fermi energy is set from 0 Ry to 0.1 Ry with “Shift Fermi energy” menu

Stereogram

The stereogram (parallel eyes and cross eyes) becomes enabled/disabled (Fig. 14).

None (Default)

Parallel
Parallel-eyes stereogram
Cross
Cross-eyes stereogram
_images/stereogram.png

The stereogram becomes enabled/disabled with “Stereogram” menu.

Tetrahedron

You change the scheme to divide into tetrahedra (tetra # 1 as default). It is experimental.

View point

Changing the view point.

Scale
Change the size of the figure.
Position
Change the xy position of the figure.
Rotation
Change angles at x-, y-, z- axis. Rotations are performed as z-y-x axis.

In each menu, first the current value is printed. then a prompt to input the new value appears (Fig. 15).

_images/setview.png

Saving images

fermisurfer does not have any functions to save images to a file. Please use the screenshot on your PC.