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Ideas of Quantum Chemistry P8

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where X means the mean value of many measurements of the quantity X . The standard deviation A represents the width of the distribution of A, i.e. Consider the product of the standard deviations for the operators A ˆ and B, ˆ taking into account that ˆ u denotes (Postulate IV) the integral | ˆ u | according to (1.19)....

Ideas of Quantum Chemistry P9

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The Magic of Quantum Mechanics. After flying about 6 m they both met the polarizers – analogues of slits A and B in the Bell procedure. A polarizer allows a photon with polarization state |0 or “parallel” (to the polarizer axis), always pass through, and always rejects any photon in the polarization state |1, or. When the polarizer is rotated...

Ideas of Quantum Chemistry P10

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The mean value of the Hamiltonian is preserved. Time-independent perturbation and the Fermi golden rule. The time-independent Schrödinger equation is the one place where stationary states can be produced as solutions of the equation. Both the stationary states, and the evolution of the non-stationary states, depend on the energy operator (Hamiltonian). If one finds some symmetry of the Hamiltonian, this...

Ideas of Quantum Chemistry P11

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Is therefore the very meaning of the dipole moment, a quantity often used in chemistry and physics, a fairy tale? If HCl has no dipole moment, then it is more understandable that H 2 does not have either. Let us stress, that our conclusion pertains to the total wave function, which has to reflect the space isotropy leading to the...

Ideas of Quantum Chemistry P12

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The Schrödinger Equation. one may obtain an accidental degeneracy, which does not follow from the symmetry of an object like a chair, but from the properties of the potential field, and is called dynamical symmetry. the chair is in the normal position: E 3 = 1.. There are no more stable states of the chair 24 and there are only...

Ideas of Quantum Chemistry P13

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The Schrödinger Equation M −J M J, quantizes its component along the z axis, and = ±1 represents the parity with respect to the inversion. As to the invariance with respect to permutations of identical particles: an acceptable wave function has to be antisymmetric with respect to the exchange of identical fermions, whereas it has to be symmetric when exchanging...

Ideas of Quantum Chemistry P14

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A 2 = D 2 (3.2) From the two solutions: A = D and A. Thus, we have. 3.1.2 THE GALILEAN TRANSFORMATION. The equality condition A = D is satisfied by the Galilean transformation, in which the two coefficients are equal to 1:. There are no apparent forces in the two coordinate systems related by the Galilean transformation. Also, the...

Ideas of Quantum Chemistry P15

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Beyond the Schrödinger Equation. It turns out that in both coordinate systems the distance of the event from the origin of the coordinate system is preserved. The square of the distance is calculated in a strange way as:. for the event (x ct). There it is! This equation enabled Hermann Minkowski to interpret the Lorentz transformation (3.28) as a rotation...

Ideas of Quantum Chemistry P16

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How to operate the N -component spinor (for N = 4 we have called them bispinors)? Let us construct the proper Hilbert space for the N-component spinors. 895), first, we will define the sum of two spinors in the fol- lowing way:. and then, the product of the spinor by a number γ:. Next, we check that the spinors form...

Ideas of Quantum Chemistry P17

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In the second row, the scalar product of spinors is used, in the third row, the Hermitian character of the operator p. The two integrals at the end cancel each other, because each of the integrals does not change when the variables are interchanged: x ↔ y.. where the equality follows from a direct calculation of the two integrals. 33...

Ideas of Quantum Chemistry P18

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Mysteri- ously enough, this pertains not only to the ionization energy, but also to the polarizability.. After the above mentioned cancellation (of p 4 and Darwin terms), retardation becomes one of the most important relativistic effects. As seen from the Ta- ble, the effect is about a 100 times larger (both for the ionization energy and the polarizability) for the...

Ideas of Quantum Chemistry P19

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A sin κx + B cos κx (4.3). 2.5), that the wave function has to be con- tinuous and, therefore, two conditions have to be fulfilled: 1. The first condition immediately gives B = 0, the second in this situation is equivalent to κL = nπ, for n = 0 1 . L x n because n = 0 has...

Ideas of Quantum Chemistry P20

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D single should increase when the particle energy E increases, but is the function D single (E) monotonic? Maybe there are some “magic” energies at which passage through the barrier becomes easier? Maybe this is what those guys in the movies use, when they go through walls.. It has been assumed that the particle has the mass of an electron...

Ideas of Quantum Chemistry P21

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number the variable ξ is proportional to the displacement x:. is the frequency of the classical vibration of a particle of mass m and a force con- stant k, H v represent the Hermite polynomials 31 (of degree v) defined as 32. ξ 2 ) dξ v and N v is the normalization constant, N v. The harmonic oscillator finger...

Ideas of Quantum Chemistry P22

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The Schrödinger equation may be easily separated giv- ing two equations, one for the centre-of-mass motion and the other for the relative motion of the two masses (see Appendix I on p. We are interested only in the second equation, which describes the motion of a particle of mass equal to the reduced mass of the two particles μ, and...

Ideas of Quantum Chemistry P23

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Various graphical representations of the hydrogen 3d 3z 2 −r 2 orbital (coordinates in Figs. (a) Isolines of the xz section of the or- bital. We may imagine xz section of the 3d 3z 2 −r 2 as two hills and two valleys (b), the hills are higher than the depth of the valleys (the plateaus in Fig. The orbital...

Ideas of Quantum Chemistry P24

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The variational method of linear combinations of functions was formulated by Walther Ritz in a paper published in Zeitschrift für Reine und Angewandte Mathematik . The method was applied by Erwin Schrödinger in his first works “Quantisierung als Eigen- wertproblem” in Annalen der Physik ibid. Egil Andersen Hylleraas, in Zeitschrift der Physik showed for the first time that the variational...

Ideas of Quantum Chemistry P25

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The first of eqs. To eliminate ψ (1) k we will use the Hermitian character of the operators. In- deed, by making the scalar product of the equation with ψ (0) k we obtain:. 20 We see the construction principle of these equations: we write down all the terms which give a given value of the sum of the upper...

Ideas of Quantum Chemistry P26

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We are on the most important branch of the TREE.. A colleague shows us the gas phase absorption spectra of the hydrogen atom and of the hydrogen molecule recorded in the ultraviolet and visible (UV-VIS), infrared (IR) and mi- crowave range. The spectrum of the hydrogen atom consists of separated narrow absorption lines. The hydrogen molecule spectrum is much more...

Ideas of Quantum Chemistry P27

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(6.5) we have ψ l H ˆ [ ψ k f k. R ψ k e = 0, which follows from the dif- ferentiation of the normalization condition 12 for the function ψ k. Grouping all the terms with f l on the left-hand side we obtain a set of N equations. 12 We assume that the phase of the...