How to plot energy diagram using gnuplot - gnuplot

Question

I have data file:
0 0 3 -0.17 6 -0.05
0 0 3 -0.23 6 0.90
0 0 3 -0.41 6 0.50
0 0 3 -0.50 6 -0.33
0 0 3 -0.20 6 0.80
I want to plot the figure like this which connects each point in the lines. Can you tell me how?

Answer 1

The following suggestion uses the plotting styles with boxxyerror, with vectors and with labels.
The zero level gets the color of the last entry because everything is plotted on top of each other. Check the following example as starting point for further tweaking.
Script:
### energy diagram
reset session
$Data <<EOD
0 0 3 -0.17 6 -0.05 A_{one}
0 0 3 -0.23 6 0.90 B_{two}
0 0 3 -0.41 6 0.50 C_{three}
0 0 3 -0.50 6 -0.33 D_{four}
0 0 3 -0.20 6 0.80 E_{five}
EOD
set key noautotitle
set xrange [-1:8]
myWidth = 0.3
plot for [i=1:3] $Data u (column(2*i-1)):(column(i*2)):(myWidth):(0):0:xtic(i*2-1) w boxxy lw 3 lc var, \
for [i=1:2] '' u (column(2*i-1)+myWidth):(column(i*2)): \
(column(2*i+1)-column(2*i-1)-2*myWidth):(column(i*2+2)-column(i*2)):0 w vec nohead lw 1 dt 3 lc var, \
'' u 5:6:7:0 w labels offset 6,0 tc var font ",16"
### end of script
Result:
Addition:
From your comments: If the levels are to close such that the labels overlap, you could add an individual offset (here in column 8).
Check the following example where the data is modified that the levels B and E are very close.
Script:
Edit after OP's comment: simplifications, with xerrorbar instead of with boxxyerror and with custom xtics
Edit 2: simplified input data
reduce the input data to the minimum
add xticlabel from columnheader
use column number as x-coordinate. Mind the difference in ...$Data u (col):col:...: e.g. if col=1, (col) is the fixed value of 1, and col is the value from column 1.
### energy diagram with individual offset of labels
reset session
$Data <<EOD
A B C Label Offset
0.0 -0.17 -0.05 A_{one} 0
0.0 -0.23 0.90 B_{two} 0.05
0.0 -0.41 0.50 C_{three} 0
0.0 -0.50 -0.33 D_{four} 0
0.0 -0.20 0.85 E_{five} -0.05
EOD
set key noautotitle
set errorbars 0
set offset 0.5,0.5,0,0
myWidth = 0.1
plot for [col=1:3] $Data u (col):col:(myWidth):0:xtic(columnhead(col)) w xerr lw 3 ps 0 lc var, \
for [col=1:2] '' u (col+myWidth):col:(1-2*myWidth):(column(col+1)-column(col)):0 \
w vec nohead lw 1 dt 3 lc var, \
'' u (3+myWidth):($3+$5):4:0 w labels left offset 1,0 tc var font ",16"
### end of script
Result: