Windows

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Energy Level Plot Window

This window can be used to display a wide variety of energy level plots. The plot below is a typical linear molecule plot, showing the rotational levels of the ground X ³Σ ^-state of SO. Plotted as a function of J, in shows the F₁ F₂ and F₃ components as a function of J. Note that BJ(J+1) has been subtracted from the vertical scale, so that the deviations from the simple BJ(J+1) pattern are clear. The actions of the various controls are listed below.

• The status bar at the bottom will show the co-ordinates of the mouse at a minimum, and will also normally show information about calculated and observed points.
• To print the plot right click on the plot and select "Copy to clipboard" and then paste it into a suitable application. For Microsoft word, and many other applications it is important to use "paste special" rather than a simple paste (otherwise the numbers producing the plot will be pasted, rather than the plot itself).

	Select which states to plot.
	Open another level Window
	Write the plotted energy levels to the Log window

Plot Type

	The options in this group control the overall appearance of the plot.
	Plot against external field, rather than quantum number. See Electric or Magnetic Field Plots for more details.
	Plot a symbol for each level. The key to the symbols will normally be shown at the top of the plot, and different symbols indicate different symmetries.
	Join associated levels with lines. The levels joined are controlled by the three options below.
	Plot both points and lines.
	Choose between starting join process from the highest energy or lowest energy point
	Try to join points with related values of quantum numbers
	Try to join points arising from same state

Energy Scale

	The options in this group control the vertical scale of the plot
	Maximum energy in plot
	Minimum energy in plot
	Refresh Plot (only needed if AutoReplot turned off in mixture)
	Adjust plot range to include all levels
	Zoom to selected vertical range
	Compress vertical scale
	Subtract number × J(J+1) from all energies plotted

Level Selection

	This group allows levels to be selected by symmetry or some other quantum numbers. The picture is for a linear molecule; alternate quantum numbers are selected for other molecule types.
	Select (or not) symmetry to plot
	Select Ω (linear molecules), Ka (asymmetric tops) |K| (symmetric tops) or v1 (Vibrating molecule).
	Select Fn (linear molecules), Kc (asymmetric tops) or Kl (symmetric tops).

x Axis

	For normal plots, this controls the x axis.
	Select quantum number for x axis
	Minimum J to include in plot
	Maximum J to include in plot

Observed Level Overlay

It is possible to compare calculated and observed energy levels, with the "observed" energy levels calculated from measured line positions and the simulated energy levels for the other state. This requires an experimental line list (a .lin file), made as described in line position fitting. To include experimental information:

1. Make sure the line list file is set in the Log window.
2. Select to plot upper state energy levels or to plot lower state energy levels.
3. Press to display the observed energy levels.
4. The display is normally clearer if is selected for the calculated energy levels.
5. If the mouse is over an experimental point it's source is displayed in the status bar; right click offers the following options:
• Edit Point: Open point under cursor in editor if possible.
• Show Line: Centre main plot on transtion
  

	Plot Upper State Observed Levels
	Plot Lower State Observed Levels
	Join observed point to calculated point
	(Re)load observations
	When plotting observed energy levels, scale the distance from the calculated position by this.

Calculation Adjustment

	This group allows the selected items to be excluded from calculations
	Exclude perturbations in plotted levels
	Set how many nuclear and electron spins to exclude from the calculation

Line Labels

None LeftOut: At left edge of plot, right justified LeftIn: At left edge of plot, left justified RightIn: At right edge of plot, right justified RightOut: At right edge of plot, left justified Start: At start of the line End: At the end of the line