Photofragmentation of the lanthanum isopropylcyclopentadienyl complex, La(iCp), was explored through time-dependent excited-state molecular dynamics (TDESMD), excited-state molecular dynamics (ESMD), and thermal molecular dynamics (MD). Simulated mass spectra were extracted from ab initio molecular dynamics simulations through a new and simple method and compared to experimental photoionization time-of-flight (PI-TOF) mass spectra. The computational results indicate that the value of excitation energy and mechanism of excitation determine the dissociation process.