We want to use oniom method to calculate aqueos water inside nanotube,in which the C atomtype and other parameters of nanotube seems not be defined. I look up previous papers, showing that the L-J parameter between two oxygen atoms as σOO = 0.315 nm and EOO = 0.1521 kcal/mol.Moreover, the L-J parameters between two carbon atoms are σCC = 0.355nm and ECC = 0.293 kJ/mol, the L-J par…

I’m very new to Q-chem and computational chemistry in general, so please keep this in mind if I don’t use the correct terminology. I calculated and NMR spectrum of a molecule of interest. IQmol displays the data fairly well. However, we’d like to “bin” similar atoms differently than what IQmol allows us to do. I’d also like to be able to zoom in on the graph, which I apparently ca…

I’ve been using vibronic and changing the quadrature grid to calculate the UV-VIS spectrum of molecules of interest to us. I’ve found that sometimes when I go to the SG-2 grid from the SG-1 grid that I can get a huge improvement in the predicted spectrum. What I mean by huge improvement is that the spectrum shifts to about the right wavelength, and the shape of the spectrum narrows…

I have a relatively symmetric structure. I ran an excited state freq/opt/freq/opt/freq process and at the end had a structure that looked good and had no imaginary frequencies. Later calculations for the ground state failed for various reasons. So to restart my vibronic calculation, I did the following: I took the geometry optimized excited state structure, the one that showed 0 i…