In our recent work [S. Noh and W. Park, Nonrelativistic quark model analysis of Tcc, ], the mass and binding energy of Tcc are found to be 3873 MeV and −2 MeV, respectively, which align with the observations reported at LHCb [R. Aaij (LHCb Collaboration), Observation of an exotic narrow doubly charmed tetraquark, ]. Based on our latest quark model approach, we extend our search for other potentially stable configurations of doubly heavy tetraquarks using our nonrelativistic quark model described in Noh and Park, [Nonrelativistic quark model analysis of Tcc, ]. Our numerical calculations indicate that the u¯s¯cb configuration is deeply bound. However, the u¯d¯cb configuration with the isospin symmetry in the light quark sector is relatively less bound. In this study, we emphasize a compulsory aspect for requiring a complete set of three-dimensional harmonic oscillator bases through the discussion of the u¯s¯cb configuration and investigate the essential differences between the u¯s¯cb and u¯d¯cb configurations. Published by the American Physical Society 2024