Some simple remarks on variational bounds in Faddeev-type formalisms

A bound on the energy obtained from the differential equation forms of Faddeev-type equations is derived. The procedure is based on the standard variation principle for the Schrödinger equation plus the observation that the ordinary Schrödinger wavefunction |ψ(i)> equals the sum of the Faddeev-type “channel wavefunctions” |ψ_λ(i)>.     

Anharmonicity in rotational and vibrational excitation of H2 by Li+ collisions

Integral cross sections for pure rotational and vibrational-rotational excitation of H₂(X¹Σ⁺_g) by Li⁺(¹S) impact are computed by close-coupling methods at 0.2, 0.6, and 1.2 eV in the c.m. system using vibrational functions that are numerical solutions of the one-dimensional radial Schrödinger equation for harmonic, Morse, and adiabatically corrected Kolos-Wolniewicz (KW) potential functions. Comparison of results employing KW and Morse functions shows excellent agreement for all transitions studied. Findings using harmonic oscillator functions, however, differ noticeably from KW and Morse values for vibrational (0 → 1) and very large rotational (Δj = 10) transitions, but are satisfactory for lower order (0 → 2, 4, 6, 8) rotational transitions.     

Integral and state-to-state cross sections for the reaction D + H2(νf) → HD(νf) + H: A quantum mechanical study within the infinite order sudden approximation

In this paper are presented quantum mechanical t-initial and t-average cross sections and rate constants for the reactions D + H₂(ν₁ = 0, 1) → HD(ν_f = 0, 1) + H. The calculations were done employing the infinite order sudden approximation. It was found that the t-average total cross sections overlap very nicely with the available classical cross sections. As for rate constants a reasonably good fit was found with available experimental results.     

Quantum mechanical reactive scattering theory

In this article we briefly discuss a number of promising approaches to the formulation of a general, numerically exact, quantum mechanical theory of fully three-dimensional reactive atom-diatom collisions. It is noted that the ability to treat the three-dimensional H + H₂ exchange reactions is pre-requisite to any demonstration of the success of a general quantum mechanical formalism for reactivescattering. However, it is also noted that the time has come for any such theory to further demonstrate the ability to go beyond this basic, elementary atom-diatom exchange reaction. It is speculated that there now exist a number of approaches which can potentially provide such a general framework for quantum reactive scattering theory. Finally, a new generalizationof the Faddeev formalism for such systems, which is capable of inclusion ofthree body forces with a completely general form for the potential surface, is presented.     

Reacting to spontaneous feedback from external customers in a university hospital laboratory

Modern quality standards for laboratories recommend the use of customer feedback in quality improvement. Spontaneous customer feedback is one method to obtain information from customers. In the present study, we analysed the feedback data from external customers (health centres and other hospitals) to our university hospital laboratory during 2001–2006. The most common subject matters of the feedback, covering 87% of a total of 95 reports, were lacking test results, suspicion of the validity of test results, return of samples in transportation boxes to customers and delays in service. On investigation, errors or defects were revealed in 78 cases. The most common errors were lacking (45 cases; 58%), erroneous (20 cases; 26%) or delayed test results (7 cases; 9%). As much as 68% of these errors took place in the pre-analytical phase of the laboratory process, occurring most commonly during specimen transfer, when entering orders into the laboratory information system at the university hospital or during sample processing. The most common underlying causes for errors were unintended errors and non-compliance with operating instructions. Latent errors were identified in 14% of the cases. Corrective actions were performed in 79% of the reported cases. It is important that the feedback reports are investigated to find out possible errors and their underlying causes so that appropriate corrective actions can be taken. When processed properly, spontaneous customer feedback is a method that can be used supplementarily to other methods to detect errors and defects in clinical laboratories and to aid in quality improvement.     

Quantum mechanical generalized phase-shift approach to atom-surface scattering: a Feshbach projection approach to dealing with closed channel effects

We have developed a new method for solving quantum dynamical scattering problems, using the time-independent Schr?dinger equation (TISE), based on a novel method to generalize a "one-way" quantum mechanical wave equation, impose correct boundary conditions, and eliminate exponentially growing closed channel solutions. The approach is readily parallelized to achieve approximate N(2) scaling, where N is the number of coupled equations. The full two-way nature of the TISE is included while propagating the wave function in the scattering variable and the full S-matrix is obtained. The new algorithm is based on a "Modified Cayley" operator splitting approach, generalizing earlier work where the method was applied to the time-dependent Schr?dinger equation. All scattering variable propagation approaches to solving the TISE involve solving a Helmholtz-type equation, and for more than one degree of freedom, these are notoriously ill-behaved, due to the unavoidable presence of exponentially growing contributions to the numerical solution. Traditionally, the method used to eliminate exponential growth has posed a major obstacle to the full parallelization of such propagation algorithms. We stabilize by using the Feshbach projection operator technique to remove all the nonphysical exponentially growing closed channels, while retaining all of the propagating open channel components, as well as exponentially decaying closed channel components.     

CS(lav) and computational study of degeneracy averaged differerential cross sections and Δm-integral cross sections: Hez.sbndCO,HDz.sbnd

CC and l-average CS calculations of degeneracy averaged differential cross sections and Δm-integral cross sections have been performed for Hez.sbndCO at E = 60 cm^?1 and E = 80 cm^?1, for HDz.sbndNe at E = 254 cm^?1, and for Hez.sbndH₂ at E = 1520 cm^?1. The l_avz.sbndCS degeneracy averaged differential cross sections are generally in good agreement with the CC cross sections. The previously observed shifts in the diffraction oscillations for odd rotationally inelastic transitions for Hez.sbndCO and HDz.sbndNe do not occur due to proper phase choice and l? = l_av choice rather than l? = 1 or l′. The l_avz.sbndCS approximation gives reliable results for most Δm-integral cross sections except for those σ_cs(jm, jm′) cross sections for which the CC cross sections σ(jm;jm′) and σ(jm′;jm) differ by a large amount.