Fortran 90 implementation of the Hartree-Fock approach within the CNDO/2 and INDO models

Despite the tremendous advances made by the ab initio theory of electronic structure of atoms and molecules, its applications are still not possible for very large systems. Therefore, semi-empirical model Hamiltonians based on the zero-differential overlap (ZDO) approach such as the Pariser-Parr-Pople, CNDO, INDO, etc. provide attractive, and computationally tractable, alternatives to the ab initio treatment of large systems. In this paper we describe a Fortran 90 computer program developed by us, that uses CNDO/2 and INDO methods to solve Hartree-Fock(HF) equation for molecular systems. The INDO method can be used for the molecules containing the first-row atoms, while the CNDO/2 method is applicable to those containing both the first-, and the second-row, atoms. We have paid particular attention to computational efficiency while developing the code, and, therefore, it allows us to perform calculations on large molecules such as C_60 on small computers within a matter of seconds. Besides being able to compute the molecular orbitals and total energies, our code is also able to compute properties such as the electric dipole moment, Mulliken population analysis, and linear optical absorption spectrum of the system. We also demonstrate how the program can be used to compute the total energy per unit cell of a polymer. The applications presented in this paper include small organic and inorganic molecules, fullerene C_60, and model polymeric systems, viz., chains containing alternating boron and nitrogen atoms (BN chain), and carbon atoms (C chain).Comment: 29 pages, 3 figures, to appear in Computer Physics Communication

Using molecular similarity to construct accurate semiempirical electron structure theories

Ab initio electronic structure methods give accurate results for small systems, but do not scale well to large systems. Chemical insight tells us that molecular functional groups will behave approximately the same way in all molecules, large or small. This molecular similarity is exploited in semiempirical methods, which couple simple electronic structure theories with parameters for the transferable characteristics of functional groups. We propse that high-level calculations on small molecules provide a rich source of parametrization data. In principle, we can select a functional group, generate a large amount of ab initio data on the group in various small-molecule environments, and "mine" this data to build a sophisticated model for the group's behavior in large molecules. This work details such a model for electron correlation: a semiempirical, subsystem-based correlation functional that predicts a subsystem's two-electron density as a functional of its one-electron density. This model is demonstrated on two small systems: chains of linear, minimal-basis (H-H)5, treated as a sum of four overlapping (H-H)2 subsystems; and the aldehyde group of a set of HOC-R molecules. The results provide an initial demonstration of the feasibility of this approach.Comment: The following article appeared in the Journal of Chemical Physics, 121 (12), 5635-5645 (2004) and may be found at http://jcp.aip.org

Stresses in the vicinity of an un-reinforced mitre intersection: an experimental and finite element comparison

The experimental investigation reported provides elastic stresses in the vicinity of the unreinforced intersection of a single 90° mitred bend, subjected to an in-plane bending moment. The specimen was extensively strain gauged on the outer surface. A small number of rosettes were also laid on the inside surface close to the welded intersection. The procedures used for the successful installation of the inside surface gauges are discussed. In the experiment, consideration was also given to deflections and rotations. Satisfactory comparisons with adaptive-p thin-shell finite element results were obtained in general and differences are explained in terms of the known experimental variables and finite element approximations. The nature of the stresses at such intersections is discussed and various methods of obtaining fatigue 'hot-spot' stresses are considered

Creatividad y apropiación de la lengua inglesa: la enseñanza y evaluación de creación literaria a estudiantes no nativos

This article examines some aspects of the relationship between the ownership of English language and its production by non-native speaker creative writers. It discusses ways in which novice creative writers may strive to control their production of text in English, without the scaffolding and structures that conventional ‘academic writing’ may both offer and impose. The article also discusses the relationship between the students attempts to control and own the English language, and the ways in which the academic assesses their writing; both in terms of their creativity and their control.Este artículo abarca algunos aspectos correspondientes a la relación entre apropiación de la lengua inglesa y su producción por parte de escritores no nativos de literatura creativa. También se analizan diferentes maneras en las que escritores novatos se esfuerzan por alcanzar un control de los textos producidos en inglés, sin el andamiaje y las estructuras que la escritura académica les podría ofrecer y al mismo tiempo, imponer. Este artículo también profundiza en la relación entre el esfuerzo por parte de los estudiantes por controlar y apropiarse de la lengua inglesa, y la manera en que el sistema académico evalúa sus textos, en términos de creatividad y control

The role of the Hermansky-Pudlak protein in lysosome biogenesis

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Control tools : Requirements of tools to control feral cats

In 2008, the background document to the ‘Threat abatement plan for predation by feral cats’ (DEWHA 2008) considered the main control techniques for feral cats as trapping, shooting and exclusion fencing. Baiting was recognised as the most cost-effective method for broad-scale control, but was not commonly employed on the Australian mainland, although it had been used successfully in island eradications (Campbell et al. 2011). A sausage bait using 1080, Eradicat, had recently been developed and employed in Western Australia (Algar and Burrows 2004), but there were concerns over its application to the eastern states where native species are less tolerant of 1080 (Johnston et al. 2011). Development of an effective, humane cat-specific toxin and bait was seen as a high priority for feral cat management in Australia (DEWHA 2008). There has been progress on this front with development of the Curiosity bait using PAPP as a toxin (Johnston et al. 2011, Johnston et al. 2012) and other toxin delivery methods (Read 2010, Read et al. 2014). There have also been further applications of Eradicat, including on the mainland (Algar et al. 2013), and other control methods, and there is a better understanding of cat ecology and impacts, which will help improve strategies for their control. A review of control techniques and their application is thus timely

The ecology and conservation of the white-winged nightjar Caprimulgus candicans

In the tradition of previous studies of threatened species, this thesis was undertaken with the aim of improving our understanding of the ecology of the White-winged Nightjar Caprimulgus candicans, and providing the information necessary to facilitate conservation efforts on its behalf. In 1998–2001, I studied a population of White-winged Nightjars at Aguará Ñu, an area of cerrado habitats within the Reserva Natural del Bosque Mbaracayú, eastern Paraguay. Over the course of three fieldwork seasons, I captured and ringed a total of 49 nightjars (34 adults and 15 young birds). Young females first bred at approximately one year old, while still in pre-definitive plumage. Young males exhibited a form of delayed plumage maturation, whereby they only attained definitive plumage following a prolonged moult spanning much of their first potential breeding season. No evidence was obtained to suggest that they succeeded in breeding while in this conspicuously intermediate state of moult. Considerable variation was noted in the plumage whiteness of definitive males, but no clear evidence was found for consistent age-related increases in white. During the breeding season, males defended small aggregated display territories, at which they conducted nuptial display flights between late August and early January. Female nightjars were responsible for all the parental care, and apparently visited male display arenas solely to obtain copulations. Chick paternity data confirmed that the study population was polygynous, with patterns of male aggregation suggestive of an exploded lek or ‘landmark’ mating system. Radio-telemetry studies showed that nightjars utilised home ranges of at least 20 to 40 hectares during the eight to ten months for which they were monitored. Home ranges contained a disproportionately large amount of young campo cerrado vegetation, but no forest or old campo cerrado habitats. When selecting foraging sites within their ranges, nightjars preferred younger and avoided older campo cerrado vegetation; wet grassland was utilised roughly in proportion to its availability. Observed patterns of habitat selection were potentially explained by the greater abundance of insect prey in younger habitats. When selecting daytime roost sites, nightjars preferred vegetation of intermediate age, reflecting their need for a balance between cover and ease of access. A more general analysis of patterns of sexual dimorphism within the Caprimulgidae showed that, although almost 80% of nightjar species exhibit some dimorphism of plumage whiteness, the study species was by far the most extreme case. The striking plumage of the male was partly explained by a strong positive relationship between wing white and openness of breeding habitats within the family. However, this failed to explain the complete absence of white in the female plumage, or the extent of white dimorphism shown by the species. The most likely explanation would appear to be that extreme plumage dimorphism occurred in conjunction with the evolution of polygyny and female-only care in this open-country species. The implications of these findings for the conservation of the White-winged Nightjar are highlighted, and recommendations are proposed for future work and conservation action.This work was funded by the Biotechnology and Biological Sciences Research Council [studentship number: 98A1S04126]