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  • 1
    Electronic Resource
    Electronic Resource
    Does squaring the quantum Monte Carlo weights give the exact quantum probability distribution? (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 2118-2120 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: It is shown that the recently-proposed method of East et al. [J. Chem. Phys. 89, 4880 (1988)] for stochastically obtaining the exact quantum mechanical probability distribution ||φ||2 is in error. The Green's function generator for the proposed process results in a Schrödinger-like equation for which ||φ||2 is not a solution. We carefully follow the logic of East et al. to discover their error.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457998
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  • 2
    Electronic Resource
    Electronic Resource
    Valence quantum Monte Carlo with ab initio effective core potentials (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 1130-1136 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Effective-core potentials (ECP's) obtained from ab initio methods are implemented in molecular quantum Monte Carlo (QMC). The theory is presented, and applied to the calculation of electron affinities (EA) of Li and Na, the ionization potential (IP) of Mg, the binding energies (De) of NaH and Na2, and the potential energy curve of Na2. In all cases ECP–QMC results are found to be as accurate as previous all-electron results. In particular, the calculated quantities (vs experimental values) are (in eV): EA(Li)=0.611±0.020 (0.620), EA(Na)=0.555±0.021 (0.546), IP(Mg)=7.637±0.026 (7.646), De (NaH) =1.954±0.073 (1.971), and De (Na2)=0.746±0.020 (0.747). In addition, the statistical precision obtained surpasses that which can be readily achieved in all-electron QMC calculations on these systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453345
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  • 3
    Electronic Resource
    Electronic Resource
    Quantum Monte Carlo calculation of the singlet–triplet splitting in methylene (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 82 (1985), S. 1983-1990 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The fixed-node quantum Monte Carlo (QMC) method is used to calculate the total energy of CH2 in the 3B1 and 1A1 states. For both states, the best QMC variationally bounded energies lie more than 15 kcal/mol (0.024 h) below the best previous variational calculations. Subtracting these energies to obtain the singlet–triplet splitting yields Te=9.4±2.2 kcal/mol. Adjusting for zero-point energies and relativistic effects, we obtain T0=8.9±2.2 kcal/mol. This result is in excellent agreement with the recent direct measurements of McKellar et al. of T0=9.05±0.06 kcal/mol, and of Leopold et al. of ∼9 kcal/mol, as well as with recent threoretical investigations which indicate an energy gap of 9–11 kcal/mol. We summarize the QMC method, discuss a possible scheme for iteratively correcting the procedure, and note that the present results were obtained using only single determinant functions for both states, in contrast to conventional ab initio approaches which must use at least two configurations to properly describe the singlet state.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.448381
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  • 4
    Electronic Resource
    Electronic Resource
    AN EMPIRICAL ANALYSIS OF THE DEGREE OF MONOPOLY THEORY OF DISTRIBUTION (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Bulletin of economic research 36 (1984), S. 0 
    Details
    ISSN: 1467-8586
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1467-8586.1984.tb00525.x
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  • 5
    Electronic Resource
    Electronic Resource
    Monte Carlo study of electron correlation functions for small molecules (1989)
    Springer
    Theoretical chemistry accounts 75 (1989), S. 353-368 
    Details
    ISSN: 1432-2234
    Keywords: Correlation functions ; Monte Carlo ; Small molecules ; Variational calculations ; Trial wave functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A study is made of electron-electron correlation functions for use in trial wave functions for small molecules. New forms are proposed that have only a few variational parameters, and these parameters have physical meanings that are easily discerned. Total energies for H2, LiH and Li2 computed using these correlation functions are presented, and comparison is made with previous forms, including the Jastrow-Pade form often used in Monte Carlo studies. We further treat the possibility that correlation depends not only on the separation of a pair of electrons but also on the location of the electron pair relative to the nuclei — indicative of a density-dependent or many body correlation effect. Our results indicate that such a many-body correlation effect is weakly present.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00526694
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  • 6
    Electronic Resource
    Electronic Resource
    Preface: What is quantum chaos? (1992)
    Springer
    Journal of statistical physics 68 (1992), S. 1-4 
    Details
    ISSN: 1572-9613
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01048834
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  • 7
    Electronic Resource
    Electronic Resource
    Overcoming the large-Z problem in quantum monte carlo (1990)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 38 (1990), S. 679-680 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Z6 scaling of computational effort in quantum Monte Carlo (QMC) results in part from a type of critical slowing down. This insight leads to an attack based on acceleration algorithms which modify the dynamics in Langevin-based simulations without changing the steady-state. Configuration space is more rapidly sampled and steps are inherently more decorrelated. A second approach uses a hybrid Metropolis-Green function Monte Carlo method which factors the core and valence wave function, and treats the former variationally with accurate trial functions, and the latter exactly in the presence of the variationally evoling core. This allows separation of the relevant core and valence time scales, and has sped up quantum simulations by over three orders of magnitude.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560382465
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