I want to plot the energy versus ky1 (eq1), but when I vary the values of the irradiation intensity (I), I find that the positive energy bands are coincide, and I don't known where the problem lies.

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    $\begingroup$ You should not use I as symbol in your calculations. It is reserved by Wolfram Language to represent the imaginary unit of the complex numbers. $\endgroup$ – m_goldberg Nov 21 at 1:58
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    $\begingroup$ Please do not post images of your work. Please post your actual Mathematica code in the form of text that can be copied and pasted into a Mathematica notebook. Without such, people who wan to help you will have do a lot of work to reproduce your problem so they can experiment with possible solutions. $\endgroup$ – m_goldberg Nov 21 at 2:00