This project aims to design ultracold molecules containing elements (preferably heavy metals) using advanced quantum chemical techniques, with the goal of finding intriguing applications in high-precision spectroscopic experiments and quantum information science. By examining the electronic and vibrational structure of these molecules, we can predict their suitability for laser cooling and also assess their potential in areas such as fundamental physics, ultracold chemistry, spectroscopy, and quantum technology. To accurately predict the internal structure of these molecules and their properties including molecular-frame dipole moment, hyperfine structure interactions, and violations of parity and charge-parity symmetry, robust quantum chemical methods that account for relativistic as well as correlation effects of electrons are essential. Thus, relativistic many-body methods, particularly relativistic coupled-cluster approaches, will be employed for the proposed research. Ultimately, this research will identify promising molecules for laser cooling to ultracold temperatures and provide theoretical insights into their properties for scientific and technological applications.