High power multi-level converters are deemed as the mainstay power conversion technology for renewable energy systems including the battery storage system, PV farm and electrical vehicle charge station. This thesis is focused on the study of three-level DC/DC converter with multi-phase interleaved structure, with coupled and integrated magnetics to achieve high power density. The proposed interleaved phased legs offer the benefit of output current ripple reduction, while inversed coupled inductors can suppress the circulating current between phase legs. Compared with conventional non-interleaving three-level DC/DC converter with non-coupling inductors, both inductor current ripple and output current ripple are largely reduced by interleaving with inverse-coupled inductors. Because of the non-linearity of the inductor coupling, the equivalent circuit model is developed for the proposed interleaving structure. The model identifies the existence of multiple equivalent inductances during one switching cycle. A combination of them determines the inductor current ripple and dynamics of the system. By virtue of inverse coupling and means of controlling the coupling coefficients, one can minimize the current ripple and the unwanted circulating current. To further reduce the magnetic volume, the four inductors in two-phase three-level DC/DC converter are integrated into one common structure, incorporating the negative coupling effects. The integrated magnetic structure can effectively suppress the circulating current and reduce the inductor current ripple and it is easy to manufacture. This thesis provides an equivalent circuit model to facilitate the design optimization of the integrated system. A prototype of integrated coupled inductors is assembled with nano-crystalline C-C core and powder block core. It is tested with both impedance analyzer and single pulse tester, to guarantee proper mutual inductance for inductor current ripple and output current ripple target. With a two-phase three-level DC/DC converter hardware, the concept of integrated coupled inductors is verified, showing its good performance in high-voltage, high-power conversion applications. / Master of Science / With the demanding energy consumption globally, there is an increasing trend for the requirement of high efficiency power converters with high power density. The application for renewable energies including the PV farm, battery storage system and electrical vehicle become more and more important for the sustainable development of society. High-power, high-voltage DC/DC converters can fulfill the role for such renewable energy power conversion. In this paper, a multi-phase multi-level DC/DC converter solution suitable for high-power, high-voltage application is analyzed and designed. With the techniques including interleaving operation and inverse coupled inductors, the power density for the power conversion is increased while keeping a high system efficiency. The discussed power converter in this thesis demonstrated a solution for high-power, highvoltage DC/DC power conversion with high efficiency. And the concept is verified with real hardware experimental results, showing its good performance for a 200kW power conversion system.

In dieser Arbeit werden Algorithmen für die Berechnung elektronischer Korrelations- und Anregungsenergien mittels der Coupled-Cluster Methode auf adaptiven Gittern entwickelt und implementiert. Die jeweiligen Funktionen und Operatoren werden adaptiv durch Multiskalenanalyse dargestellt, was eine Basissatz unabängige Beschreibung mit kontrollierter numerischer Genauigkeit ermöglicht. Gleichungen für die Coupled-Cluster Methode werden in einem verallgemeinerten Rahmen, unabhängig von virtuellen Orbitalen und globalen Basissätzen, neu formuliert. Hierzu werden die amplitudengewichteten Anregungen in virtuelle Orbitale ersetzt durch Anregungen in n-Elektronenfunktionen, welche durch Gleichungen im n-Elektronen Ortsraum bestimmt sind. Die erhaltenen Gleichungen können, analog zur Basissatz abh¨angigen Form, mit leicht angepasster Interpretation diagrammatisch dargestellt werden. Aufgrund des singulären Coulomb Potentials werden die Arbeitsgleichungen mit einem explizit korrelierten Ansatz regularisiert. Coupled-Cluster singles mit genäherten doubles (CC2) und ähnliche Modelle werden, für geschlossenschalige Systeme und in regularisierter Form, in die MADNESS Bibliothek (eine allgemeine Bibliothek zur Darstellung von Funktionen und Operatoren mittels Multiskalenanalyse) implementiert. Mit der vorgestellten Methode können elektronische CC2 Paarkorrelationsenergien und Anregungsenergien mit bestimmter numerischer Genauigkeit unabhängig von globalen Basissätzen berechnet werden, was anhand von kleinen Molekülen verifiziert wird / In this work algorithms for the computation of electronic correlation and excitation energies with the Coupled-Cluster method on adaptive grids are developed and implemented. The corresponding functions and operators are adaptively represented with multiresolution analysis allowing a basis-set independent description with controlled numerical accuracy. Equations for the coupled-cluster model are reformulated in a generalized framework independent of virtual orbitals and global basis-sets. For this, the amplitude weighted excitations into virtuals are replaced by excitations into n-electron functions which are determined by projected equations in the n-electron position space. The resulting equations can be represented diagrammatically analogous to basis-set dependent approaches with slightly adjusted rules of interpretation. Due to the singular Coulomb potential, the working equations are regularized with an explicitly correlated ansatz. Coupled-cluster singles with approximate doubles (CC2) and similar models are implemented for closed-shell systems and in regularized form into the MADNESS library (a general library for the representation of functions and operators with multiresolution analysis). With the presented approach electronic CC2 pair-correlation energies and excitation energies can be computed with definite numerical accuracy and without dependence on global basis sets, which is verified on small molecules.

Text in English / This study offers a close look at Andrew Niccol’s (b 1964) satirical film S1mOne from a biocultural perspective emphasising the technological simulation of a Hollywood celebrity and the farce ensuing from her creation. The film is based on Niccol’s assumption that the hypertrophied culture into which he places his cultural object will be one in which human traits of sociality will be well advanced and the highly demanding genre of satire will be entertaining, persuasive, and on occasion punitive in its ridicule of Hollywood. The study makes a contribution to the idea that a cultural object/text operates as a rapid mechanism for propagating cognition — it shows how Niccol has adapted to less than optimal conditions in his world of Hollywood — in this case he parodies the role of the director of Hollywood films in the figure of Taransky. Cognition is understood as that series of mental processes which include attention, memory, learning (from mimicry as well as other forms), problem solving, ratiocination, and making decisions. Niccol relies on his audience's embodied capacities and skills of recognition, thinking, feeling, remembering, and accounting for his message to be understood. Niccol’s technical skill in editing his narrative to emphasise the satire of the narrative of Taransky and Simone is a critical part of the film’s success. Interpersonal and social propagation of cognition is achieved through reference to other cultural artefacts recalling a variety of similar ideas used in film and other visual creations. The cultural significance of the simulacrum, Simone, is that she is a vehicle for and a form of socially propagated cognition. The powerful imagistic impression of film helps to structure internalised cognitive artefacts in the viewers who are expected to reflect on their habits of viewing and thinking. When a film, artwork, poem or novel is analysed, then such a cultural object becomes a vehicle of and for propagating cognition. / Art History, Visual Arts and Musicology / D. Litt. et Phil. (Art History)

No presente trabalho utiliza-se um m´etodo multi-escala para estudar de forma te´orica as intera¸coes nao lineares entre o oceano e a atmosfera atrav´es de ressonancia onda-onda. Desenvolve-se uma hierarquia de modelos acoplados oceano-atmosfera nao lineares que foram escalonados convenientemente para representar as principais escalas de variabilidade clim´atica (i.e., intrasazonal, interanual, e decenal). A enfase dos modelos desenvolvidos foi dado para a regiao tropical. As fontes de nao linearidade inclu´das no modelo sao de dois tipos: I) nao linearidade intr´nsica (advectiva) e II) nao linearidade relacionada com os termos da f´sica e ambas sao abordadas neste trabalho. Para obter as equa¸coes que regem a dinamica de intera¸coes ressonantes a partir da hierarquia de modelos acoplados, aplicou-se um m´etodo perturbativo multi-escala. As solu¸coes sao escritas em termos de solu¸coes de ordem dominante e solu¸coes seculares. Para as solu¸coes de ordem dominante e seculares utilizam-se as fun¸coes base do problema linear, em uma aproxima¸cao do tipo Galerkin. As propriedades das fun¸coes base permitem calcular de forma anal´tica os coeficientes de intera¸cao associados com os termos nao lineares, assim como tamb´em permitem projetar estes termos nos modos de oscila¸cao natural do sistema (ressonancia). Com este m´etodo obt´em-se modelos reduzidos que permitem determinar as contribui¸coes de diversos processos para a evolu¸cao em escala lenta de um determinado modo de variabilidade natural. Para aplicar estes conceitos ao problema de acoplamento oceano-atmosfera utiliza-se como Ansatz (hip´otese inicial para a solu¸cao do problema) um tripleto composto por duas ondas atmosf´ericas e uma onda oceanica, sendo uma onda de Kelvin e de Rossby na atmosfera e uma onda Kelvin no oceano. O tripleto escolhido representa uma aproxima¸cao de v´arios fenomenos encontrados na regiao tropical, e.g. o desenvolvimento do El Nino, a intera¸cao da oscila¸cao de Madden-Julian com o oceano, a intera¸cao entre el Nino e variabilidade intrasazonal. No presente trabalho ´e mostrado que existe a ressonancia envolvendo ondas atmosf´ericas e oceanicas e que a modula¸cao em baixa frequencia produto desta ressonancia pode afetar desde escalas r´apidas sin´oticas equatoriais, intrasazonais, interanuais e at´e variabilidade da ordem de dezenas de anos. Palavras chave: Dinamica Equatorial nao linear, Intera¸coes Ressonantes, Modelos Acoplados Oceano-Atmosfera, El Nino, Oscila¸cao de Madden Julian, Oscila¸coes Decenais (Decadal) / In the present work a multiscale method is used to study resonant nonlinear wave-wave interactions between the ocean and the atmosphere. A hierarchy of coupled atmosphere-ocean models is developed using typical scalings found in the tropical region with the aim to represent some of the dominant modes of climate variability (intraseasonal, interannual and decadal). The sources of nonlinearity included into model are of two types: I) intrinsic nonlinearity (advective form) and II) nonlinearity related to physical terms. A multi-scale perturbation method is applied to obtain equations governing dynamics of ressonant interactions. The solutions are described in terms of dominant and secular solutions. For the dominant modes basis functions of the linear problem are used in a approximation of the Galerkin type. The properties of the basis functions allows the analytical computation of the interaction coefficients associated with non-linear terms and the projection into the natural oscillation modes of the system (resonance). Using this method it is possible to obtain reduced models to determine the contributions of several processes to the slow time evolution of a specific mode of natural variability. To apply these concepts to the problem of atmosphere-ocean coupling an Ansatz composed of a three waves (two atmospheric Rossby and Kelvin waves and an ocean Kelvin wave) is used. The triad chosen represents a aproximation of several phenomena found in the tropical region, e.g. desenvolving of El Nino, interaction of the Madden-Julian oscillation with the ocean, interaction between El Nino and intra-seasonal variability, etc. It is shown that system allows a resonance involving atmospheric and oceanic waves and that the low-frequency modulation resulting from these ressonance can affect the system from fast equatorial synoptic scales to decadal timescales, including the intermediate scales i.e., intraseasonal and interannual.

A produção de petróleo e gás em campos brasileiros é cada vez mais proveniente de regiões com águas profundas e situadas longe da costa, chegando a distâncias de mais de 100 km, como, por exemplo, na Bacia de Campos ou de Santos. Devido à falta de infra-estrutura e às características do petróleo desses campos, a cadeia de abastecimento e o sistema de exportação da produção possuem grande importância para a indústria offshore. Uma maneira usual para a exportação da produção é através de dutos submarinos, onde o óleo e/ou a gás flui das plataformas diretamente para o continente. Com esta infra-estrutura é possível a utilização de sistemas de produção sem capacidade de armazenamento e, conseqüentemente, torna-se desnecessário o uso de navios para o alívio da produção. No entanto, devido à qualidade do óleo e às distâncias entre os poços e a costa em alguns campos brasileiros, a utilização dos oleodutos mostra-se uma solução pouco viável. Por este motivo, é bastante comum o uso de FPSOs ou semi-submersíveis conectadas a sistemas auxiliares, como o FSO (Floating Storage and Offloading). Nas plataformas, outra característica importante e desejada é tornar viável o uso de um sistema de completação seca (árvore de Natal acima da linha dágua) com o objetivo de diminuir, significativamente, os custos operacionais envolvidos. Esse tipo de completação é utilizado, com excelência, por unidade do tipo TLWP ou Spar, devido ao baixo nível dos movimentos e acelerações observadas nestas plataformas. Entretanto, as condições ambientais severas amplificam as dificuldades para encontrar um sistema com grande capacidade de armazenamento e que permita o uso de completação seca. Neste contexto, pesquisadores e engenheiros estão sendo obrigados a desenvolver novos conceitos capazes de atender a essa demanda. Desta forma, uma nova solução, considerando um FPSO e uma TLWP operando a uma curta distância e trabalhando de forma acoplada com a conexão garantida por cabos sintéticos vem sendo estudada. Essencialmente, o grande atrativo deste conceito é o fato de que toda a produção e o armazenamento são concentrados no FPSO e a TLWP é responsável pela perfuração e extração dos hidrocarbonetos através de risers verticais. Assim o sistema trabalhando de forma conjunta possui capacidade de armazenamento e permite o uso da completação seca. Nesta dissertação, foi realizado um estudo sobre a evolução deste novo conceito, dividido em três fases. A primeira focada no dimensionamento do sistema de conexão e ancoragem das unidades e em uma investigação da interação hidrodinâmica entre as unidades de forma a mostrar a viabilidade do sistema. A segunda fase, focada na validação dos resultados por meio da comparação com os testes realizados no modelo em escala do NMRI (National Maritime Research Institute - Japão). Finalmente, a terceira fase, com foco no redimensionamento do sistema de amarração e no sistema de conexão, com base nos resultados obtidos na segunda fase. / The oil and gas production in Brazilian fields are commonly found in deep water and situated far away from the coast, reaching distances of more than 100 km as, for example, in the Campos Basin or Santos Basin. Due to the heavy oil and lack of pipeline infrastructure found in these fields, not only subsea equipments that must support high pressure but also logistics problems such as supply chain and production exportation system play an important role for the offshore industry. A usual way to export the production is to concentrate it in hubs of submarine pipelines which flows the oil or gas from the platforms to the continent. This infrastructure makes possible the use of no storage production systems and, consequently, releases the use of the shuttle tanks employment. However, due to the quality of the oil and the distances between the wells and the coast, some Brazilian fields do not allow the use of the pipelines to export their production. For this reason, is quite common to use FPSO and semi-submersible aided by auxiliary systems such as the FSO (Floating Storage and Offloading) units. Another important and desired characteristic of production platforms is to make it feasible to install a dry Christmas tree system aiming to decrease, significantly, operational costs involved. This feature is performed, with excellence, by TLWP and Spar units due to the low level of motions and accelerations observed in these platforms. Harsh environmental conditions can bring difficulties to find a solution of a system with both storage and dry tree system capability. In this context, researchers and engineers are being forced to develop new technological systems capable to support this demand. In this way, a new solution considering a FPSO and a TLWP coupled in a short distance by synthetic ropes has being studied. Essentially, the attractive feature of this concept is the fact that the production is performed by the FPSO whereas the TLWP is responsible to support the risers and drilling facilities turning the system coupled, equipped with a dry Christmas tree and with the possibility to storage the production. By now, the concept evolution has been divided in three phases. The first phase concerned about an advanced research focusing on the connection and mooring system development and the hydrodynamic interaction between the units and having in mind the verification of the concept feasibility. The second phase, concerned about the results validation by a comparison with scale model tests performed in the NMRI (National Maritime Research Institute Japan). Finally, the third phase, has the focus in the mooring and connection system resizing based on the results obtained on second phase.

La conjugaison de phase ultrasonore à couplage par l’air basée sur une céramique magnétostrictive et une membrane de filtration poreuse pour la microscopie et la vélocimétrie de micro écoulements a été développée. Dans ce but, dans le cadre de l’acoustique géométrique un système d’équations pour décrire mathématiquement le passage par l’interface entre l’élément actif du système de conjugaison de phase confocale – milieu de propagation a été développé.On a développé et réalisé une technique de codage de phase par m-séquence pour l’enregistrement des faibles signaux conjugués en phase. Cette technique a permis de travailler plus efficacement avec fort bruit et des signaux qui se trouvent sous le niveau de bruit. Aussi cette technique a permis d’améliorer une méthode de vélocimétrie des écoulements gazeux.On a développé et réalisé une technique d’adaptation d’impédance acoustique basée sur la membrane de filtration poreuse imprégnée par de l’huile. Cette technique a permis d’optimiser les conditions de transmission de l’onde à l’interface air–ferrite aux fréquences basse dans bande du MHz.Les applications possibles de l’effet de conjugaison de phase paramétrique à la vélocimétrie des écoulements gazeux et à la microscopie à couplage par l’air ont été présentées. L’application de l’effet de conjugaison de phase permet d’améliorer les performances des méthodes de vélocimétrie et de microscopie ultrasonores à couplage par l’air. Les méthodes élaborées a repoussé les limites d’applications pratiques de l’effet de conjugaison de phase et peuvent être utilisées pour le développement des dispositifs en vélocimétrie, microscopie et tomographie ultrasonore des écoulements gazeux / Air-coupled wave phase conjugation technique, based on magneto-acoustic interaction and porous membrane filters, for microscopy and velocity measurements of gas micro flows is under investigation. For this reason in the frame of ray acoustics the base system of equations for mathematical model of phase conjugate wave passage through the interface active element of con-focal WPC system – medium of propagation is developed. The phase coding technique by pseudonoise M-sequence was used for registration of weak acoustical phase conjugate signals. This method has allowed to work more effectively with strong noisy and being under noise level phase conjugate signals. Also this method has allowed improving a method of gas flow velocimetry.It is developed and realized the technology of acoustical matching on base of thin polycarbonate porous membrane filters impregnated by oil. This technology has allowed optimizing the conditions of wave transmission through the interface air–ferrite in the low megahertz frequency range.Possible applications of phase conjugate waves in air are shown. Results of investigations of air-coupled wave phase conjugation technics can serve for drawing up of new methods ultrasonic velocimetry and microscopy in technical industrial applications. The elaborated methods expand limits of application and can be used for development of devices of ultrasonic microscopy, tomography and velocimetry of gas micro flows

This thesis presents a nonadiabatic (4-body) description of the hydrogen-antihydrogen system at a nonrelativistic level. The properties of the system, the rearrangement processes and the possible existence of resonance states are investigated by using a variational method for coupled arrangement channels, the Gaussian Expansion Method, and the stabilization method. The 4-body basis set is optimized by means of prediagonalization of 2-body fragments. In paper I, a mass-scaling procedure of the Born-Oppenheimer potential is introduced for the description of the relative motion between hydrogen and antihydrogen. The nonadiabaticity of the system is investigated in paper II.

Many-Body Perturbation Theory is put to test as a method for reliable calculations of the electron-electron interaction in two-dimensional quantum dots. We show that second order correlation gives qualitative agreement with experiments on a level which was not found within the Hartree-Fock description. For weaker confinements, the second order correction is shown to be insufficient and higher order contributions must be taken into account. We demonstrate that all order Many-Body Perturbation Theory in the form of the Coupled Cluster Singles and Doubles method yields very reliable results for confinements close to those estimated from experimental data. The possibility to use very large basis sets is shown to be a major advantage compared to Full Configuration Interaction approaches, especially for more than five confined electrons. Also, the possibility to utilize two-electron correlation in combination with tailor made potentials to achieve useful properties is explored. In the case of a two-dimensional quantum dot molecule we vary the interdot distance, and in the case of a two-dimensional quantum ring we vary the ring radius, in order to alter the spectra. In the latter case we demonstrate that correlation in combination with electromagnetic pulses can be used for the realization of quantum logical gates. / At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Manuscript.

This study aims to investigate the behaviour of low-order beam and plate elements especially for their application to laminated structures. The merits and dements of the existing elements are brought out and new low-order elements with better interpolation polynomials are proposed. Two new beam elements are proposed for laminated composite beams that yield better representation of twist due to material coupling. Out of the two elements developed, one is based on the conventional formulation and the other on the coupled-field formulation, both capturing material induced coupling. The beam developed using coupled field formulation shows a novel way of obtaining a fully coupled interpolation function for field variables using the complete set of equilibrium equations for the composite beams. The element has shown a superior coarse mesh performance. These elements can practically capture plate behaviour in beam elements for a wide range of plate thickness. The locking problems in conventional 4-node quadrilateral elements, such as shear locking and geometric locking are studied. Various techniques available in literature to remedy these problems are also studied. A suite of QUAD4 with conventional techniques such as. Reduced Integration, Field Consistency, Mixed Interpolation of Tensorial strain Components, Assumed Natural Strain, Discrete Shear Gap, Incompatible modes Q6 and QM6 is developed. An effort is made to combine these techniques to develop new element that yields improved performance. The element is shown to exhibit improved performance for certain cases. Several four-node rectangular elements are developed based on the coupled-field techniques. First two new-coupled elements are formulated that employ Sabir's [101] plane bending formulation with drilling degree of freedom, and the plate bending rotations are generated using equilibrium equations. However, since Sabir's plane bending interpolation polynomials yielded inaccurate performance for composites, it led to development of elements with fully coupled field formulations. Finally, two new 4-node rectangular elements are developed using coupled-field formulations with six and seven dof freedom per node respectively. Here the interpolation polynomials are derived using the complete equilibrium equations. The elements are extensively tested for static deflection, dynamics and buckling of isotropic and laminated plates/beams. The elements show superior coarse mesh convergence. Several problems pertaining to vibration and buckling of composite plates/beams are solved using the elements developed in this work.

Extensive theoretical studies on the ground and excited state properties of systems containing heavy atoms have shown that accurate prediction of transition energies and related properties requires the incorporation of both relativistic and higher order correlation and relaxation effects as these effects are strongly inter- wined. The relativistic and dynamical electron correlation effects can be incor- porated in many-electron systems through a variety of many-body methods like configuration interaction (CI), coupled cluster method (CCM) etc. which are very powerful and effective tool for high precision description of electron correlation in many-electron systems. In this thesis, we investigate the relativistic and correlation effects in heavy atomic and molecular systems using these two highly correlated many-body methods. It is well recognized that, heavy polar diatomic molecules such as BaF, YbF, TlF, PbO, etc. are the leading experimental candidates for the search of violation of Parity (P ) and Time-reversal (T ) symmetry. The experimental detection of such P,T-odd effects in atoms and molecules has important consequences for the theory of fundamental interactions or for physics beyond the standard model (SM). For instance, a series of experiments on TlF have already been reported which provide the tightest limit available on the tensor coupling constant C , proton electric dipole moment (EDM) dp , etc. Experiments on YbF and BaF molecules are also of fundamental significance to the study of symmetry violation in nature, as these experiments have the potential to detect effects due to the electron EDMde. It is therefore imperative that high precession calculations are necessary to interpret these ongoing (and perhaps forthcoming) experimental outcome. For example, the knowledge of the effective electric field E(characterized by Wd) at the unpaired electron is required to link the experimentally determined P,T-odd frequency shift with the electron EDM de. We begin with a brief review of P,T-odd effects in heavy atoms and polar diatomics and the possible mechanisms which can give rise to such effects, in particular, the one arises due to the intrinsic electron EDM de. The P,T-odd interaction constant Wd is computed for the ground (2∑ ) state of YbF and BaF molecules using all-electron DF orbitals at the restricted active space (RAS) CI level. The RASCI space used for both systems in this calculation is sufficiently large to incorporate important core-core, core-valence, and valence-valence electron correlation effects. In addition to Wd, we also report the dipole moment (µe ) for these systems to assess the reliability of the method. The basis set dependency of Wd is also analyzed. The single reference coupled cluster (SRCC) method, developed by the cluster expansion of a single determinant reference function, is one of the most sophisticated method for treating dynamical correlation effects in a size-extensive manner. The non-uniqueness of the exponential nature of the wave operator diversifies the methods in multi-reference context. The multi-reference coupled cluster (MRCC) strategies fall within two broad classes: (a) State-Universal (SU), a Hilbert-space approach and (b) Valence-Universal (VU), a Fock-space approach. In this thesis, we shall be mainly concerned with the VU-MRCC which unlike SU-MRCC uses a single wave operator that not only correlates the reference functions, but also all the lower valence (or the so called subdued) sectors, obtained by deleting the occupancies systematically. The linear response theory (LRT) or equation of motion (EOM) method is another possible alternative which is nowadays extensively used to compute the atomic and molecular properties. Although, the CCLRT or EOM-CC method is not fully extensive in nature, this method has some distinct advantages over the traditional VU-MRCC theory. Further, for one-valence problem like ionization processes, the CCLRT/EOM-CC is formally equivalent to VU-MRCC, and hence, size-extensive. In this thesis, the core-extensive CCLRT and core-valence extensive (all electron) VU-MRCC methods are applied to compute the ground and excited state properties of various atomic and molecular systems (HCl, CuH, Ag, Sr, Yb and Hg) using nonrelativistic and relativistic (for heavy atoms) spinors. The similarities and differences in the structure of these two formalisms are also addressed. We also investigate the ground and excited state properties of HCN which is a system of astrophysical importance. This system has raised interest among the astrophysicists due to its detection in the atmosphere of Titan and Carbon stars. HCN has also been identified via radio-techniques in both comets and interstellar atmosphere. In the ash-photolysis of oxazole, iso-oxazole, and thiozole a transient band system was observed in the region 2500-3050 Å. This band system was attributed to a meta-stable form of HCN, i.e, either HNC or triplet HCN. We carry out detailed theoretical investigations using CCLRT and complete active space self-consistent field (CASSCF) method to characterize this unidentified band and other experimentally observed transitions.