I saw that some research papers added hydrogen to the geometry they were studying in Gaussian 9, even though that geometry (C2N nanosheet) didn't have hydrogen. I've also seen that adding hydrogen to a structure (like a C2N 2D nanosheet) eliminates the negative frequency, but gaussian 9 frequency calculation gives negative frequency mode even without adding hydrogen in C2N 2D nanosheet.
However in Dmol3 calculation, Dmol3 does not require adding extra hydrogen. So I wanted to know that is this ok to add extra hydrogen in a geometry??? or is it wrong process.
I've included two C2N structures below. One has extra hydrogen (in Gaussian 09), and the other doesn't (in Domol3)
Hi
In large systems like these, and if you are doing periodic calculations, you don't have to worry too much about small negative frequencies under 100 cm-1. As they are a result of the hessian calculations of the sheet
Did you optimize your unit cell by the way?
Ismail Badran I didnt apply periodic conditions. I used gaussian to optimize this structure at B3LYP/6-311G(d,p) level of theory..
Ismail Badran All vibrational frequencies are positive when i added extra hydrogen atoms. To avoid negative frequencies I needed to add hydrogen atom in the system cause without hydrogens the system shows several negative frequencies. (Like the first picture)
Though in actual C2N nanosheet there is no hydrogen atom there.
So I wanted to know that is this ok to add hydrogen in gaussian 9 frequency calculation to avoid negative frequencies???
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