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Showing 1 to 20 of 29 for “"Diffusion Monte Carlo"”.
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Exact property estimation from diffusion Monte Carlo with minimal stochastic reconfiguration /
Our objective is to develop a diffusion Monte Carlo (DMC) algorithm to estimate the exact expectation values, ($o|^|^o), of multiplicative operators, such as polarizabilities and high-order hyperpolarizabilities, for isolated atoms and molecules. The existing forward-walking pure diffusion Monte …
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Investigation into the properties and application of the Diffusion Monte Carlo method
… shall be a discussion of the properties of the Diffusion Monte Carlo (DMC) method and its applications. The discussion shall cover the basic theory behind the algorithm and the class of problems it is designed to solve: quantum systems. The algorithm will prove to be adept in producing the …
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Towards routine modelling of condensed phases with the accuracy of quantum Diffusion Monte Carlo
… limitations. First, we demonstrate that quantum diffusion Monte Carlo calculations provide a high-accuracy description of a molecular crystal PES. These calculations establish: (i) a reference dataset to benchmark cost-effective electronic structure methods; (ii) insights into competing …
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From Hypernuclei to Hypermatter: a Quantum Monte Carlo Study of Strangeness in Nuclear Structure and Nuclear Astrophysics
… work presents the recent developments in Quantum Monte Carlo calculations for nuclear systems including strange degrees of freedom. The Auxiliary Field Diffusion Monte Carlo algorithm has been extended to the strange sector by the inclusion of the lightest among the hyperons, the Λ particle. …
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Spin Polarization of Ground State Electron Gas at Low Densities
… of materials. In this work we use Quantum Monte Carlo simulations to study the spontaneous polarization of electron gas at low densities, for both two and three dimensions. Quantum Monte Carlo is a powerful method to tackle many-body Fermion problems, and its high accuracy has been …
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Pionless Effective Field Theory: Building the Bridge Between Lattice Quantum Chromodynamics and Nuclear Physics
… is solved by means of the Auxiliary Field Diffusion Monte Carlo method. A linear optimization procedure has been used to recover the correct structure of the ground state wavefunction. {\eftnopi} as revealed to be an appropriate theory to describe light nuclei both in nature, and in the …
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An investigation into the phase stability of manganese oxide using quantum Monte Carlo and insights into materials prediction in the barium-ruthenium-sulfur phase space
… of manganese oxide using fixed node dif- fusion Monte Carlo (DMC). Manganese oxide is a correlated, antiferromagnetic material that has proven to be challenging to model from first principles across a variety of approaches. Unlike conventional density functional theory and some hybrid …
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Quantum Monte Carlo With a *Stochastic Poisson Solver
"Quantum Monte Carlo (QMC) is an extremely powerful method to treat many-body systems. Usually QMC has been applied in cases where the interaction potential has a simple analytic form, like the 1/r Coulomb potential. However, in a complicated environment as in a semiconductor heterostructure, the …
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Quantum monte carlo with a stochastic potential solver
"Quantum Monte Carlo (QMC) is an extremely powerful method to treat many-body systems. Usually QMC has been applied in cases where the interaction potential has a simple analytic form, like the 1=r Coulomb potential. However, in a complicated environment as in a semiconductor heterostructure, the …
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A quantum Monte Carlo study of the high-pressure phases of solid hydrogen
Variational and Diffusion Monte Carlo are powerful computational methods which can afford accurate estimates of the ground state properties of quantum many-body problems. We have applied these Monte Carlo methods to the high pressure phases of solid hydrogen to elucidate those parts of the phase …
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Quantum Monte Carlo studies of dense hydrogen and two-dimensional Bose liquids
Quantum Monte Carlo techniques; in their various incarnations, calculate ground state or finite temperature properties of many-body quantum systems. We apply the path-integral Monte Carlo method to hydrogen at densities and temperatures in the regime of cooperative thermal and pressure …
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Application of quantum Monte Carlo methods to homogeneous electron and electron-hole systems
… is concerned with the application of quantum Monte Carlo methods to two model systems: the spin-polarised homogeneous electron gas, and a hole-doped electron gas. Electronic structure theory is briefly reviewed before discussing in more detail the quantum Monte Carlo methods used in this …
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A quantum Monte Carlo study of the two-dimensional electron gas
Quantum Monte Carlo has recently made great progress as a computational tool for quantum many-body systems. We have extended previous Monte Carlo methods to study both ground state and excited states of the two-dimensional electron gas. For ground state properties we have used variational and …
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Backflow and pairing wave function for quantum Monte Carlo methods
Quantum Monte Carlo (QMC) methods are a class of stochastic techniques that can be used to compute the properties of electronic systems accurately from first principles. This thesis is mainly concerned with the development of trial wave functions for QMC. An extension of the backflow transformation …
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Stability of Topological States and Crystalline Solids
… the stability of molecules using variational and diffusion Monte Carlo. By incorporating the matrix of force constants directly into the algorithms, we find that we are able to improve the efficiency and accuracy of atomic relaxation and eigenfrequency calculation. We test the performance on a …
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Improved wave functions for quantum Monte Carlo
Quantum Monte Carlo (QMC) methods can yield highly accurate energies for correlated quantum systems. QMC calculations based on many-body wave functions are considerably more accurate than density functional theory methods, and their accuracy rivals that of the most sophisticated quantum chemistry …
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Monte Carlo methods: application to hydrogen gas and hard spheres
Quantum Monte Carlo (QMC) methods are among the most accurate for computing ground state properties of quantum systems. The two major types of QMC we use are Variational Monte Carlo (VMC), which evaluates integrals arising from the variational principle, and Diffusion Monte Carlo (DMC), which …
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Low-dimensional quantum systems
… and tungsten-based materials. Using the diffusion Monte Carlo method, which is statistically exact for these systems, we extract binding energies of the complexes for a complete set of parameters of the model. Our results are compared with theoretical and experimental work on …
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Energetics of neutral interstitials in germanium
… of germanium n-MOSFETs, including enhanced diffusion of donor atoms which leads to electrical deactivation. The preferential generation of self-interstitials via proton irradiation reduces donor diffusion and offers a promising route for effective fabrication of n-type devices. Fairly little …
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Electron-ion correlation and finite-size effects in quantum Monte Carlo simulations
… mixture of electrons and ions using the quantum Monte Carlo method. In many electronic structure studies, purely electronic properties are calculated on a static potential energy surface generated by ``clamped'' ions. This can lead to quantitative errors, for example, in the prediction of the …
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