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Showing 1 to 20 of 125 for “"wavefunction"”.
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The Phase of the Cosmological Wavefunction
… constrain cosmological correlators and the wavefunction of the universe (also referred to as the cosmological wavefunction) in inflationary spacetimes. Using the Effective Field Theory of Inflation (EFToI), the first part of the thesis classifies all parity-even graviton bispectra from local …
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The cosmological bootstrap and the analytic wavefunction
… implies a set of consistency relations among wavefunction coefficients in perturbation theory, and these relations can be generalized to fields with any mass and integer spin. Unitarity, alongside locality and scale invariance, also implies the vanishing of four-point parity odd correlators at …
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Projector Quantum Monte Carlo Methods for Linear and Non-linear Wavefunction Ansatzes
… Quantum Monte Carlo method for non-linear wavefunction ansatzes and its application to strongly correlated materials. This new approach is partially inspired by a prior application of the Full Configuration Interaction Quantum Monte Carlo (FCIQMC) method to the three-band ($p-d$) Hubbard …
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Accurate Computation Of Molecular Properties From Novel Applications Of Quantum Mechanical Wavefunction Methods
High-accuracy quantum mechanical (qm) wavefunction methods have been applied to compute molecular properties of weakly-bound clusters. This work focuses on both extending the applicability of robust theoretical methods to larger systems and also determining the inherent accuracy of ab initio …
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A gaussian wavefunction for the isoelectronic sequence of two-electron homonuclear diatomic molecules
<p>The Gaussian wavefunctions recently reported by Kim an d Hirschfelder were found to be in error due t o incorrect formulas for two integrals . The interaction potentials calculated in terms of t he corrected wave-f unctions are found to be in reasonable accord with the exact results of Kolos and …
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Reactive Scattering of an Atom by a Diatom: The Coupled Arrangement Wavefunction Method
… The present method, the coupled arrangement wavefunction (CAW) method, is developed and specialized for e('-) + H scattering. Computational results are presented for this system with an internal basis set of up to three functions. These results find a Feshbach resonance below the first …
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Wavefunction-based method for excited-state electron correlations in periodic systems - application to polymers
… a systematic method for determining correlated wavefunctions of extended systems in the ground state as well as in excited states is presented. It allows to fully exploit the power of quantum-chemical programs designed for correlation calculations of finite molecules. Using localized …
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The role of spatial size and orientation of electronic wavefunction in exciton dissociation at van der Waals interfaces
… of the orientation of the delocalized electron wavefunction and the interfacial energy landscape in the exciton dissociation (ED) process are studied in order to understand mechanisms that control the ED efficiency. A number of donor–acceptor interfaces including organic/organic and …
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Novel Ansätze for Stochastic Coupled Cluster
… algorithmic difficulty to encode a MRCC wavefunction based on a fully arbitrary reference space and cluster truncation level. The technique is shown to be highly accurate even in regimes where single-reference CC methods fail, while only incurring a linear increase in memory requirements. …
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Optimization of trial wave functions for use in quantum Monte Carlo with application to LiH
Methods for both partial and full optimization of wavefunction parameters are explored, and these are applied to the LiH molecule. A partial optimization can be easily performed with little difficulty. But to perform a full optimization we must avoid a wrong minimum, and deal with …
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Topological materials and quantum entanglement
… phase transition, based on a single topological wavefunction. This is achieved by performing extensive partitions of the wavefunction, such as a checkerboard partition. Implementing this technique in one dimension naturally involves the use of tensor networks, which will be reviewed and then …
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Dimensionally Regulated On-Shell Renormalisation In QCD And QED
… and is applicable to on-shell mass and wavefunction renormalisation. <br></br><br></br> After an extensive review of the relevant areas of renormalisation, and of the rôle of quark masses in current algebra, we go on to use the extended technique to extract the fermion mass and …
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Controlling light emission with shaped electron wavefunctions
… emission from a free electron by shaping the its wavefunction has been a long-standing question. In this work, we use both a semi-classical formalism and a QED formalism to show that Bremsstrahlung radiation can be tailored by altering the electron superposition states. Using the semi-classical …
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Approximate Spin Extended Hartree-Fock theory
… the Generalized Valence Bond form of the ASEHF wavefunction is employed, a particularly useful description of the molecule is obtained. Specifically, the success or failure of the Woodward-Hoffman becomes transparent when the system is analyzed in terms of this wavefunction.
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An Indeterminacy-based Local Approach and Ontology for Quantum Theory
… ontologies for quantum theories, namely, wavefunction realism and primitive ontology, and argue that it has certain benefits that they lack without some of their costs, such as non-locality. Due to the overall benefits of GQT compared with these widely debated ontological frameworks, and …
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Studies of and methods for electronic properties of large chemical systems
… model, to good result. Third, we develop a wavefunction-in-wavefunction embedding theory for strongly correlated systems. We base our work on Density Matrix Embedding Theory (DMET). We extend the original DMET equations to account for correlation in the bath via an antisymmetrized geminal …
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The Cosmological Implications of Unitarity
… a set of relations among the coefficients of the wavefunction of the universe in such an expanding epoch, which we name the cosmological optical theorem. We also show that this result can equivalently be understood as a single cut rule that relates diagrams at different orders in perturbation …
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Theoretical and computational investigations of the electron and spin correlation in chemical bonds, building a predictive bonding model with generalized valence bond theory
… non-dynamical correlations, yet retaining a wavefunction that is a single product of spatial orbitals, although with a more general spin function than that used in HF theory. Because of GVB’s ability to describe the making and breaking of chemical bonds and describe the bonding in molecules …
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A High Order Correction of the Energy of a One Dimensional Model of an H2+ Molecule
The ground state electron wavefunction of some molecules has a non-zero angular momentum about the internuclear axis. Molecular rotational momentum can couple with this angular momentum, splitting the energy degeneracy of the two directions of motion about the internuclear axis. Performing a …
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A quantum Monte Carlo study of the high-pressure phases of solid hydrogen
… particles by incorporating them in the trial wavefunction and avoids the Born-Oppenheimer and harmonic approximations. Our trial wavefunction uses single-body solutions from a mean-field calculation coupled with standard pair potential terms to achieve the most accurate results to date. …
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