Chapter 2 Wave Mechanics

Roland L. Omnes

Anthony Duncan A, Michel Janssen B

Abstract This chapter explores Schrödinger’s introduction of wave mechanics. After briefly covering Schrödinger’s earlier work, it turns to the investigations that led him to write a four-part paper in 1926 introducing and applying wave mechanics. The chapter provides a detailed analysis of these four papers, in which the analogy of the new theory to the Hamilton-Jacobi formulation of classical mechanics plays a central role, as well as the paper written in between the second and the third installment on the relation between wave and matrix mechanics. The chapter also discusses Schr "odinger’s original interpretation of his wave functions and the reception of his theory by the physics community.

Caio Lima Firme

In this chapter shows some applications of matrix and wave mechnanics. The equivalence between matrix mechanics and wave mechanics is explored in this chapter. Another approach for this equivalence is indicated as well. The Heisenberg equation of motion is applied to the quantum virial theorem and quantum theory of atoms in molecules (QTAIM) in next section. It is introduced afterwards that the Heisenberg’s matrix mechanics is applied to the helium atom leads to the concept of quantum resonance and chemical bond. Next, the use of the matrix mechanics and wave mechanics to obtain the uncertainty principle is discussed and its derivation is also given. Subsequently, Dirac’s quantum mechanics – an amalgamation of matrix mechanics and wave mechanics – is introduced. Finally, the importance of the commutation of the quantum operators to the quantum mechanics is discussed followed by some basic quantum principles from the Copenhagen interpretation. A couple of examples and exercises is also available in this chapter.(156 words).

Helmut J. Fischbeck, Kurt H. Fischbeck

Helmut J. Fischbeck, Kurt H. Fischbeck

Sergey V. Gaponenko

Let us return from optics to mechanics and explore the analogy to its fullest extent. In optics the old system of mechanics corresponds to intellectually operating with isolated mutually independent light rays. The new undulatory mechanics corresponds to the wave theory of light . Erwin Schrödinger, Nobel lecture , 1933 In this chapter we shall see that electromagnetic waves and electrons feature a number of common properties under conditions of spatial confinement. Simple and familiar problems from introductory quantum mechanics and textbook wave optics are recalled in this chapter to emphasize the basic features of waves in spatially inhomogeneous media. Herewith we make a first step towards understanding the properties of electrons and electromagnetic waves in nanostructures and notice that these properties in many instances are counterparts. Different formulas and statements of this chapter can be found in handbooks on quantum mechanics and wave optics. A few textbooks on quantum mechanics do consider analogies of propagation and reflection phenomena in wave optics with those in wave mechanics. Isomorphism of the Schrödinger and Helmholtz equations In Chapter 2 we discussed that an electron in quantum mechanics is described by the wave function, the square of its absolute value giving the probability of finding an electron at a specific point in space. This function satisfies the Schrödinger equation (2.56) which is the second-order differential equation with respect to space and the first-order differential equation with respect to time.