Atomic and molecular complex resonances from real eigenvalues using standard (hermitian) electronic structure calculations

Complex eigenvalues, resonances, play an important role in large variety of fields in physics and chemistry. For example, in cold molecular collision experiments and electron scattering experiments, autoionizing and pre-dissociative metastable resonances are generated. However, the computation of complex resonance eigenvalues is difficult, since it requires severe modifications of standard electronic structure codes and methods. Here we show how resonance eigenvalues, positions and widths, can be calculated using the standard, widely used, electronic-structure packages. Our method enables the calculations of the complex resonance eigenvalues by using analytical continuation procedures (such as Pad\'{e}). The key point in our approach is the existence of narrow analytical passages from the real axis to the complex energy plane. In fact, the existence of these analytical passages relies on using finite basis sets. These passages become narrower as the basis set becomes more complete, whereas in the exact limit, these passages to the complex plane are closed. As illustrative numerical examples we calculated the autoionization resonances of helium, hydrogen anion and hydrogen molecule. We show that our results are in an excellent agreement with the results obtained by other theoretical methods and with available experimental results

Elements of control

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, 1999.Includes bibliographical references (leaves 234-240).How many different types of control relations exist? Is the classical distinction between Obligatory Control (OC) and Non-Obligatory Control (NOC) well-founded? What semantic and syntactic properties of infinitives determine their place in the control typology? How is the "understood subject" PRO linked to the controller? This thesis investigates these questions in two steps: First, we establish a typology of control and characterize the empirical profile of each type; second, we propose mechanisms of derivation and interpretation to account for the different types . The OC category is shown to consist of two subtypes, Exhaustive Control (EC) and Partial Control (PC). Tense in EC complements is null, and PRO must be referentially identical to the controller; Tense in PC complements is contentful, and PRO need only include the controller (although matching in syntactic number is still required). OC establishes an Agree relation between a matrix functional head and either PRO (in EC) or the infinitival Agr (in PC). The latter is parasitic on T-to-C movement occurring in tensed complements. Control via Agr blocks the transmission of semantic number from the controller to PRO, giving rise to the PC effect. The OC/NOC distinction is traced to the position of the infinitive: VP-internal clauses fall under OC, extraposed and intraposed clauses under NOC - a corollary of the CED, which constrains Agree. Extraposed clauses may be interpreted and pronounced in different positions - a claim that is supported by asymmetries between psych and non-psych predicates in Super-Equi constructions. Converging evidence from extraction confirms that infinitives displaying OC and those displaying NOC occupy different positions at LF although the same position at PF. As for the interpretation of OC, the choice of controller is subject to complex semantic/pragmatic considerations, rather than some syntactic locality principle. We also argue that OC cannot be reduced to predication, at least in the domain of adjectival complementation. Systematic contrasts between subject-gap and object-gap infinitives show that the former may denote either propositions (when occurring as arguments) or predicates (when occurring as modifiers). Thus, two sources exist for subject gaps - PRO (universally available) or A-bar trace (language-particular).by Idan Landau.Ph.D

Affected Experiencers

Numerous languages permit an NP that is not selected by the verb to be added to a clause, with several different possible interpretations. We divide such non-selected arguments into possessor, benefactive, attitude holder, and affected experiencer categories, on the basis of syntactic and semantic differences between them. We propose a formal analysis of the affected experiencer construction. In our account, a syntactic head Aff(ect) introduces the experiencer argument, and adds a conventional implicature to the effect that any event of the type denoted by its syntactic sister is the source of the experiencer’s psychological experience. Hence, our proposal involves two tiers of meaning: the at-issue meaning of the sentence, and some not-at-issue meaning (an implicature). A syntactic head can introduce material on both tiers. Additionally, we allow two parameters of variation: (i) the height of the attachment of Aff, and (ii) how much of the semantics is at-issue and how much is an implicature. We show that these two parameters account for the attested variation across our sample of languages, as well as the significant commonalities among them. Our analysis also accounts for significant differences between affected experiencers and the other types of non-selected arguments, and we also note a generalization to the effect that purely not-at-issue non-selected arguments can only be weak or clitic pronouns

The Evolution of Compact Binary Star Systems

We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

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A Selectional Criterion for Adjunct Control

Non UBCUnreviewedFacult