Recent advances in multireference methods / edited by K Hirao.

Format:

Book

Contributor:

Hirao, K. (Kimihiko)

Series:

Recent advances in computational chemistry ; v. 4.

Recent advances in computational chemistry ; v. 4

Language:

English

Subjects (All):

Quantum chemistry.

Quantum theory.

Physical Description:

1 online resource (225 p.)

Place of Publication:

Singapore ; River Edge, NJ : World Scientific, c1999.

Language Note:

English

Summary:

Recently, accurate ab initio quantum computational chemistry has evolved dramatically. In particular, the development of multireference-based approaches has opened up a whole new area and has also had a profound impact on the potential of theoretical chemistry.The multiconfigurational SCF (MCSCF)/CASSCF method is an attempt to generalize the Hartree-Fock (HF) model and to treat real chemical processes, where nondynamic correlation is important, while keeping the conceptual simplicity of the HF model as much as possible. Although MCSCF/CASSCF itself does not include dynamic correlations, it pro

Contents:

FOREWORD; AUTHOR LIST; CONTENTS; THE CONFIGURATION-DRIVEN APPROACH FOR MULTIREFERENCE CONFIGURATION INTERACTION CALCULATIONS; 1 Introduction; 2 Theoretical Background; 3 Table CI; 4 Implementation of Direct CI; 5 Internal MO Grouping of Configurations; 6 Timing Results and Outlook; 7 Conclusion; Acknowledgments; References; MULTI-REFERENCE PERTURBATION THEORY; 1 Introduction; 2 Perturbation Theory; 2.1 Partitioned perturbation theory; 2.2 Multi-reference many-body perturbation theory; 2.3 Examples; Conclusion; Acknowledgment; References

RESPONSE THEORIES BASED ON A STATE-SPECIFIC MULTI-REFERENCE COUPLED CLUSTER FORMALISM1 Introduction; 2 A State-Specific Coupled Cluster Theory with a 'Relaxed Coefficient' Reference Function; 3 Evaluation of Second-order Static Properties from SS-MRCC Using Perturbed Orbitals in a Finite Field; 3.1 Theory; 3.2 Pilot Molecular Applications; 4 A Linear Response Theory Based on State-Specific MRCC Induced by an Excitation Operator; 4.1 Theory; 4.2 Connectedness of MR-CCLRT Equations; 4.3 Pilot Applications; 5 Summarizing Remarks; 6 Acknowledgements; References

MULTI-REFERENCE COUPLED PAIR APPROXIMATION: a state-universal approach of a CEPA type variant of MRSDCI1 Introduction; 1.1 Brief notes on the CI method; 1.2 Brief note on cluster expansion method; 2 CEPA type variants of MRSDCI; 2.1 MRCPA method; 2.2 Comparison with other multi-reference based CEPA type methods; 2.3 Size-consistency; 2.4 Computational results and comparison; 3 Summary; Acknowledgments; References; ANALYTIC ENERGY GRADIENTS FOR SECOND-ORDER MULTIREFERENCE PERTURBATION THEORY; 1 Introduction; 1.1 Multireference perturbation theory

1.2 Analytic energy derivatives of multireference perturbation theory2 Lagrange multiplier method; 3 MC-QDPT Lagrangian; 3.1 The MC-QDPT energy expression to the second order; 3.2 The constraining conditions for determining the parameters; 3.2.1 Determination of molecular orbitals; 3.2.2 Determination of the reference functions; 3.2.3 Definition of the orbital energies; 3.2.4 The diagonalization condition of the effective Hamiltonian; 3.2.5 The definition of some auxiliary parameters; 3.3 The MC-QDPT Lagrangian; 4 The linear equations for the Lagrange multipliers

The multipliers for diagonalization of the effective Hamiltonian4.2 The multipliers for the one- and two-electron integrals; 4.3 The multipliers for the definition of energy shift; 4.4 The multipliers for the orbital energies; 4.5 The linear equations for the multipliers for the CI coefficients of the reference functions; 4.6 The multipliers for the MO rotations in the invariant doubly occupied and external orbital subspaces; 4.7 The linear equations for the multipliers for the MO rotations and the Cl coefficients of the CASSCF functions

4.8 The multipliers for the MO orthonormalization conditions

Notes:

Description based upon print version of record.

Includes bibliographical references.

ISBN:

9789812812186

9812812180