In contrast, generating mass spectra through QC calculations does not rely on empirical rules or experimental data. Such approaches offer insights into fragmentation processes and reaction mechanisms. The quantum chemical electron ionization mass spectrometry (QCEIMS) software , later renamed QCxMS after the addition of collision induced dissociation (CID) ionization and published as open-source , simulates the ionization and fragmentation process by employing QC principles to generate mass spectra in silico. Besides ab initio calculations , the package supports semiempirical quantum mechanical (SQM) methods for increased throughput. SQM modeling provides ionization potentials for high-temperature molecular dynamics (MD) and mass spectra modeling. The simplicity in parametrization, using hybrid density functional theory (DFT) reference data, enhances SQM's accessibility and efficiency. Despite potential electron delocalization overestimation, SQM excels in handling metallic systems and covalent bond dissociation, but requires corrections for optimal performance in directional electrostatic effects like halogen bonds. A standout feature is SQM's easily adaptable, element-specific parameters, enriching method versatility. Whereas DFT remains the most accurate, SQM-based MD is more than 100 times faster than pure DFT-based MD.