The nano rod is confined in x and y axis and I have doubt if I should take vacuum not only in z direction but in all three axes. As taking vacuum slows down the calculation indefinitely.

I am not able to find any relevant research article. Majority of the articles have used MD simulation or SIESTA package. Those who have used VASP have not made nanorod itself.

Please let me know if anyone has faced similar issue or knows how to proceed.

Thanks in advance.