In this article the concept of mass is analyzed based on the special and general relativity theories and particle (quantum) physics. The mass of a particle (m=E(0)/c^2) is determined by the minimum (rest) energy to create that particle which is invar
iant under Lorentz transformations. The mass of a bound particle in the any field is described by m<E80)/c^2 and for free particles in the non-relativistic case the relation m=E/c^2 is valid. This relation is not correct in general, and it is wrong to apply it to the radiation and fields. In atoms or nuclei (i.e. if the energies are quantized) the mass of the particles changes discretely. In non-relativistic cases, mass can be considered as a measure of gravitation and inertia.
By the use of integer and noninteger n-Slater Type Orbitals in combined Hartree-Fock-Roothaan method, self consistent field calculations of orbital and lowest states energies have been performed for the isoelectronic series of open shell systems K [A
r]4s^0 3d^1 2(D) (Z=19-30) and Cr+ [Ar] 4s^0 3d^5 6(S) (Z=24-30). The results of calculations for the orbital and total energies obtained from the use of minimal basis sets of integer- and noninteger n-Slater Type Orbitals are given in tables. The results are compared with the extended-basis Hartree-Fock computations. The orbital and total energies are in good agreement with those presented in the literature. The results are accurately and considerably can be useful in the application of non-relativistic and relativistic combined Hartree-Fock-Roothaan approach for heavy atomic systems.
