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  • 1
    Electronic Resource
    Electronic Resource
    On the restricted step method coupled with the augmented Hessian for the search of stationary points of any continuous function (1997)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 62 (1997), S. 153-165 
    Details
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In any optimization using the augmented Hessian technique, the step is not restricted to any length. Since the restriction of the step at each iteration is very important in order to achieve good convergence, we present a coupled method such that the augmented Hessian automatically gives both the adequate length of the step and the correct Hessian structure. The method is showed for the minima and saddle points of any order. © 1997 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    How good is a Broyden-Fletcher-Goldfarb-Shanno-like update Hessian formula to locate transition structures? Specific reformulation of Broyden-Fletcher-Goldfarb-Shanno for optimizing saddle points (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 19 (1998), S. 349-362 
    Details
    ISSN: 0192-8651
    Keywords: Broyden-Fletcher-Goldfarb-Shanno formula ; update Hessian formula ; transition structures ; optimization ; saddle points ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Based on a study of the Broyden-Fletcher-Goldfarb-Shanno (BFGS) update Hessian formula to locate minima on a hypersurface potential energy, we present an updated Hessian formula to locate and optimize saddle points of any order that in some sense preserves the initial structure of the BFGS update formula. The performance and efficiency of this new formula is compared with the previous updated Hessian formulae such as the Powell and MSP ones. We conclude that the proposed update is quite competitive but no more efficient than the normal updates normally used in any optimization of saddle points.   © 1998 John Wiley & Sons, Inc.   J Comput Chem 19: 349-362, 1998
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
    Electronic Resource
    Electronic Resource
    A reduced-restricted-quasi-Newton-Raphson method for locating and optimizing energy crossing points between two potential energy surfaces (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 18 (1997), S. 992-1003 
    Details
    ISSN: 0192-8651
    Keywords: location of funnels ; conical intersections ; crossing points ; reduced-quasi-Newton-Raphson method ; restricted step algorithm ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We present a method for the location and optimization of an intersection energy point between two potential energy surfaces. The procedure directly optimizes the excited state energy using a quasi-Newton-Raphson method coupled with a restricted step algorithm. A linear transformation is also used for the solution of the quasi-Newton-Raphson equations. The efficiency of the algorithm is analyzed and demonstrated in some examples. © 1997 John Wiley & Sons, Inc. J Comput Chem 18:992-1003, 1997
    Additional Material: 10 Tab.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 4
    Electronic Resource
    Electronic Resource
    Analysis of the convergence of the general coupling operator method for one-configuration-type wave functions (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 19 (1998), S. 368-376 
    Details
    ISSN: 0192-8651
    Keywords: general coupling operator ; coupling operator ; wave functions ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: We comment on the convergence of the general coupling operator for all types of one-configuration or multiconfigurational wave functions that still preserve the one-configuration structure for the energy expression. The choice on the best arbitrary real and antisymmetric parameters inherent in the coupling operator methodology is discussed, giving a theoretical reason. Another type of coupling operator is defined, presented, and analyzed. Finally, we give some numerical examples related to the low-lying electronic states of a cluster model for K2NiF4 solid.   © 1998 John Wiley & Sons, Inc.   J Comput Chem 19: 368-376, 1998
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 5
    Electronic Resource
    Electronic Resource
    Calculation of clustered eigenvalues of large matrices using variance minimization method (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 19 (1998), S. 1777-1785 
    Details
    ISSN: 0192-8651
    Keywords: clustered eigenvalues ; large matrices ; variance minimization method ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The autoadjusting perturbation theory method is presented and developed to calculate eigenpairs of a square matrix. The procedures to simultaneously compute a cluster of eigenpairs by variance minimization are also given. Finally, numerical examples are reported.   © 1998 John Wiley & Sons, Inc.   J Comput Chem 19: 1777-1785, 1998
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
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