UID:
almafu_9959232614502883
Umfang:
1 online resource (244 p.)
ISBN:
1-283-63585-2
,
981-281-971-1
Serie:
Recent advances in computational chemistry ; v. 2
Inhalt:
The quantum Monte Carlo (QMC) method is gaining interest as a complement to basis set ab initio methods in cases where high accuracy computation of atomic and molecular properties is desired. This volume focuses on recent advances in this area. QMC as used here refers to methods that directly solve the Schrödinger equation, for example, diffusion and Green's function Monte Carlo, as well as variational Monte Carlo. The latter is an approach to computing atomic and molecular properties by the Monte Carlo method that has fundamental similarities to basis set methods with the exception that the l
Anmerkung:
Description based upon print version of record.
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CONTENTS; PREFACE; Chapter 1: Analytical Wavefunctions from Quantum Monte Carlo Simulations; 1. Introduction; 2. The Least Squares Procedure (LSQ); 3. Weighted least squares (WLSQ); 4. Comparing the variational and the least squares wavefunction; 5. Calculations; 5.1. Particle in the box; 5.2. He l'S; 5.2.1. Six-term Hylleraas wavefunction; 5.2.2.Twenty term Hylleraas wavefunction; 5.3. He l3S; 5.4. H2X1Σ+g; 6. Conclusions; Acknowledgments; Chapter 2: Quantum Monte Carlo: Direct Determination of the Difference between True and Trial Wavefunctions; 1 Introduction
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2 The Difference Method in Simple Diffusion QMC3 Combination with Importance Sampling; 4 Illustrative Example: Partiele-in-a-Box; 5 Illustrative Example: Hydrogen Atom; 6 Accurate Calculations for the Helium Atom; 7 Accurate Calculations for LiH; 8 Discussion; 9 Acknowledgments; References; Chapter 3: Atomic Calculations Using Variational Monte Carlo; 1. Introduction; 2. Generating configurations with few electrons; 3. Generating configurations with many electrons; 4. Optimizing the parameters in the trial wavefunction; 5. Choosing the form of the trial wavefunction
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6. Calculating the ground state energy7. Simple properties; 8. Future prospects; Acknowledgments; Appendix A Nonlinear Minimization; References; Chapter 4: Recent Progress in QMC Simulations of Systems with Multiple Time Scales: Hybrid Nonadiabatic QMC; 2. Introduction; 3. Form of the Nonadiabatic Wave Function; 4. Approach; 5. Results; 6. Discussion; 7. Appendix A: Algorithm Pseudocode; 8. References; Chapter 5: Quantum Monte Carlo Calculations with Multi-Reference Trial Wave Functions; 1. Introduction.; 2. Generation of CSFs for QMC calculations.
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3. Selection of the dominant CSFs for the ground states of the atoms B to F.4. Fixed-node PDMC calculations with different types of trial wave functions.; 5. Computational details.; 6. Comparison with previous QMC and other ab initio calculations.; Acknowledgment.; Appendix A. Coupling schemes for the CSFs used in QMC calculations.; Appendix B. The explicit construction of spin-free CSFs.; References; Chapter 6: Quantum Monte Carlo Calculation of Atoms and Molecules; 1. Quantum Monte Carlo Method; 2 . QMC Calculations on Atoms; 2 .1. Calculations on Small Atoms
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2 .2. Model Potential Method for Large Atoms2 .3 Application to chemical reaction; 3. QMC Calculations on Molecules; 3.1 GFMC with Nodal Release; 3.2. Maximum Entropy Method; 3 .3. Simplification of Released-node GFMC; 4 . Atoms and Molecules Containing a Positron; 4.1 Binding Energies of Positronium Halides; 4 .2. Binding Energy of PsCH3; References; Chapter 7: Quantum Monte Carlo with Pseudopotentialsfor Electronic Structure of Atoms and Molecules; I. INTRODUCTION; II. VARIATIONAL AND DIFFUSION MONTE CARLO; A. Variational Monte Carlo; B. Diffusion Monte Carlo
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III. PSEUDOPOTENTIALS IN QUANTUM MONTE CARLO
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English
Weitere Ausg.:
ISBN 981-02-3009-5
Sprache:
Englisch
