The integration of data-driven materials research and materials informatics has become a significantapproach to enhancing traditional computational materials science. The density functional theory has proved itself to be a powerful tool to analyze experimentally observed results and to provide a theoretical understanding. In this talk, I am going to present our study of the evolution of Fermi surface topology and anomalous Hall conductivity in a well-known Dirac semimetal Cd3As2 upon the application of external Zeeman magnetic field using first-principles computational methods and a minimal k.p model. Here for the first time, I showed presence of higher order Weyl nodes of chirality ±2. Also, I shall present our study of an intermetallic material NdAlSi to show multiple Weyl nodes and it supported experimental observation of the nesting vector from quantum oscillation measurement. It provided a rare example of Weyl fermions driving collective magnetism. It summarizes the interplay of various degrees of freedom such as charge, spin, and orbital in correlated electron systems leading to interesting properties and that being studied with the help of computational methods.