UV-Vis spectra comparison between MS results and experiment data

Hi,

I followed the steps and settings in the VAMP tutorials to try to calculate the UV-Vis spectrum of benzene(C6H6). Then, I wondered if the result is similar to experimentally derived spectrum, and found that it seemed to be some differences(as figure). For example, the most important characteristic peak of benzene(254nm) did not apear in the simulation result.(I performed ab initio calculations using DMol3, but these differences did not change) Thus, I want to know how to obtain more accurate simulation results in comparision with experimental findings.

Thanks.