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RELATIONS IN THE SECOND QUANTIZATION. WAVE MECHANICS IN THE CONFIGURATION SPACE AND THE PROBLEMS OF THE SECOND ORDER IN CALCULATION OF PROBABILITIES

Georges Bodiou

Jan 1, 19540 citations

Useful variational principle for the scattering length for the target ground-state wave function imprecisely known

Robert Blau, Larry Rosenberg, Larry Spruch

A minimum principle for the calculation of the scattering length, applicable when the ground-state wave function of the target system is known precisely, has been available for some time. When, as is almost always the case, the target wave function is imprecisely known, a minimum principle is available but the simple minimum principle noted above is not applicable. Further, as recent calculations show, numerical instabilities usually arise which severely limit the utility of even an ordinary variational approach. The difficulty, which can be traced to the appearance of singularities in the variational construction, is here removed through the introduction of a minimum principle, not for the true scattering length, but for one associated with a closely connected problem. This guarantees that no instability difficulties can arise as the trial scattering wave function and the trial target wave function are improved. The calculations are little different from those required when the target ground-state wave function is known, and, in fact, the original version of the minimum principle is recovered as the trial target wave function becomes exact. A careful discussion is given of the types of problems to which the method can be applied. In particular, the effects of the Pauli principle, and the existence of a finite number of composite bound states, can be accounted for.A minimum principle for the calculation of the scattering length, applicable when the ground-state wave function of the target system is known precisely, has been available for some time. When, as is almost always the case, the target wave function is imprecisely known, a minimum principle is available but the simple minimum principle noted above is not applicable. Further, as recent calculations show, numerical instabilities usually arise which severely limit the utility of even an ordinary variational approach. The difficulty, which can be traced to the appearance of singularities in the variational construction, is here removed through the introduction of a minimum principle, not for the true scattering length, but for one associated with a closely connected problem. This guarantees that no instability difficulties can arise as the trial scattering wave function and the trial target wave function are improved. The calculations are little different from those required when the target ground-state wave function is known, and, in fact, the original version of the minimum principle is recovered as the trial target wave function becomes exact. A careful discussion is given of the types of problems to which the method can be applied. In particular, the effects of the Pauli principle, and the existence of a finite number of composite bound states, can be accounted for.

Physical Review AApr 1, 19775 citations

On the Method of "Second Quantization" in Phase Space

I︠u︡. L. Klimontovich

Journal of Experimental and Theoretical PhysicsJan 1, 195818 citations

Second Quantization of the General Many Fermion Operator

Edward R. Pike

The second-quantized equivalent of the general particle-conserving operator in the configuration space of Slater determinants is found by a direct calculation. The usual one- and two-particle operators are found as special cases and their equivalence with the corresponding configuration-space operators is thus shown without a lengthy comparison of either signs or matrix elements.

Proceedings of the Physical SocietyMar 1, 19634 citations

Cluster Integrals and the Ground State of Bosons with Repulsive Interactions

H. A. Gersch, V. H. Smith

The properties of a Bose system of particles with repulsive interactions have previously been treated using perturbation theory in the formalism of second quantization. Others have also considered this problem by dealing with the wave function in configuration space, using the theory of cluster expansions. In these latter papers, variation with respect to a parameter in a trial function for the ground state has been shown to yield a ground-state energy close to the exact asymptotic expressions obtained from perturbation theory. The connection between the two methods is not immediately obvious from these cluster expansion treatments. It is shown here that, as one might expect, the cluster integral method can be handled so that it is completely equivalent to the pair approximation in perturbation theory.The properties of a Bose system of particles with repulsive interactions have previously been treated using perturbation theory in the formalism of second quantization. Others have also considered this problem by dealing with the wave function in configuration space, using the theory of cluster expansions. In these latter papers, variation with respect to a parameter in a trial function for the ground state has been shown to yield a ground-state energy close to the exact asymptotic expressions obtained from perturbation theory. The connection between the two methods is not immediately obvious from these cluster expansion treatments. It is shown here that, as one might expect, the cluster integral method can be handled so that it is completely equivalent to the pair approximation in perturbation theory.

Physical ReviewAug 1, 19606 citations

On the correctness of the approximate second quantization method

Bratislav S. Tosic

physica status solidi (b)Dec 1, 19719 citations

2∗ Conﬁguration space and second quantization

Abstract

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2∗ Conﬁguration space and second quantization

Abstract

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