We establish a new iterative method for computing rigorous lower bounds for the ground-state energies of all atoms and ions. The accuracy of the resulting bounds depends on two ingredients: the quality of the initial energy estimate and the quality of the used upper bound for the maximum number of bound electrons,
Nc(Z), as a function of the nuclear charge
Z>0. In particular, this new method allows us to establish the explicit lower bound
E(N,Z)≥−0.8710N1/3Z2 for the ground-state energy
E(N,Z) of the atom/ion with
N∈N electrons and nuclear charge
Z∈(0,N], thereby considerably improving the best known constant
A=(3/2)1/3≈1.1447 in the estimate
E(N,Z)≥−AN1/3Z2 for
0<Z≤N and coming much closer to the best possible constant given by the Thomas-Fermi asymptotics
limN→∞∣E(N,N)∣N−7/3=−ETF(1)≈0.7687 derived in Adv. Math., 23(1) by Lieb and Simon. To demonstrate the potential and the limits of our method, we also compute explicit lower bounds for the ground-state energies
E(N,N) of all atoms with
2≤N≤86 and we compare them with the bounds obtained in J. Chem. Phys., 62(8) by Hertel, Lieb, Thirring and the bounds obtained by Seco in his dissertation. Finally, we also provide a uniqueness result for the expectation values of the kinetic, potential and interaction energies on the ground-state space.
The Schrödinger equation is the cornerstone of quantum mechanics and is used to determine the energy levels of the hydrogen atom. However, in the teaching of Quantum Chemistry, many students tend to regard the solutions of the Schrödinger equation as purely mathematical results without fully understanding the physical origin of quantum energy levels. In this paper, an approximate model of the hydrogen atom is first developed based on the Heisenberg uncertainty principle and the Coulomb potential. This model is then used to derive the Bohr radius and the ground-state energy by minimizing the total energy function. Subsequently, the time-independent Schrödinger equation is formulated and solved by the method of separation of variables in spherical coordinates to obtain the exact energy spectrum of the hydrogen atom. The results demonstrate that both the approximate model and the exact solution predict the same ground-state energy, E1 = −13.6 eV, while the Schrödinger equation further generalizes this result to the quantized energy spectrum, En = −13.6/n2. These findings indicate that the solutions of the Schrödinger equation are not "miraculous" mathematical outcomes but rather the inevitable consequences of the fundamental principles of quantum mechanics. This approach provides a clearer physical interpretation of quantum energy levels and offers significant pedagogical value for the teaching of Quantum Chemistry.
Abstract The Heisenberg uncertainty relations are cornerstones of quantum theory. Yet care is required in applying them. While they determine the lowest energy level in some systems, such as the isotropic three-dimensional harmonic oscillator, they fail to do so in other systems, notably, the hydrogen atom. This failure has been overlooked in many textbooks and pedagogic articles. The failure arises due to the singularity of the Coulomb potential. To elucidate the point, we present four subfamilies of position probability distributions. By delineating the limitations in applying position-momentum uncertainty to the hydrogen atom, we hope to improve the teaching and learning of modern physics.
A modified uncertainty principle coupling the intervals of energy and time can lead to the shortest distance attained in course of the excitation process, as well as the shortest possible time interval for that process. These lower bounds are much similar to the interval limits deduced on both the experimental and theoretical footing in the era when the Heisenberg uncertainty principle has been developed. In effect of the bounds existence, a maximal nuclear charge Ze acceptable for the Bohr atomic ion could be calculated. In the next step the velocity of electron transitions between the Bohr orbits is found to be close to the speed of light. This result provides us with the energy spectrum of transitions similar to that obtained in the Bohr’s model. A momentary force acting on the electrons in course of their transitions is estimated to be by many orders larger than a steady electrostatic force existent between the atomic electron and the nucleus.