Double- and triple-zeta Slater-type basis sets with common exponents

Double- and triple-zeta basis sets of Slater-type functions (STFs) are deve loped for the 17 atoms from He to Ar. For computational economy, the expone nts of STFs corresponding to the same atomic subshell are restricted to be common. Instead, the principal quantum numbers of the STFs are thoroughly o ptimized within the framework of integer values to reduce the energy loss d ue to the common exponent restriction.