Make sure that TD-DFPT package is installed (QE website), then the following tutorial might be useful http://www.quantum-espresso.org/tutorials/shanghai-2013/hands-on-tddft/ and for advanced discussion this could be useful https://www.researchgate.net/post/How_can_we_calculate_the_emission_spectrum_of_a_molecule_using_Gaussian

Dear Danish,

thank you so much for answer to my question. the links that you attached in answer are very helpful to me.

thanks again, and nice to meet you sear.

Hello Danish Shamoon ,

the link you have provided for tutorial is showing not exist. Please can you help me. I am also looking to find the optical properties of two dimensional materials.

Hello Radha,

The links used to be working at the time the old answer was posted. I hope you can find new tutorials on the subject. Good luck.

ok Danish Shamoon