Author
Renzo Cimiraglia
Other affiliations: University of Pisa, Rovira i Virgili University
Bio: Renzo Cimiraglia is an academic researcher from University of Ferrara. The author has contributed to research in topics: Ab initio & Excited state. The author has an hindex of 33, co-authored 130 publications receiving 7566 citations. Previous affiliations of Renzo Cimiraglia include University of Pisa & Rovira i Virgili University.
Papers published on a yearly basis
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TL;DR: In this article, two types of zero-order Hamiltonians are proposed, both are bielectronic, incorporating the interactions between electrons in the active orbitals, therefore introducing a rational balance between the zeroorder wave function and the outer-space.
Abstract: The present work presents three second-order perturbative developments from a complete active space (CAS) zero-order wave function, which are strictly additive with respect to molecular dissociation and intruder state free. They differ by the degree of contraction of the outer-space perturbers. Two types of zero-order Hamiltonians are proposed, both are bielectronic, incorporating the interactions between electrons in the active orbitals, therefore introducing a rational balance between the zero-order wave function and the outer-space. The use of Dyall’s Hamiltonian, which puts the active electrons in a fixed core field, and of a partially contracted formalism seems a promising compromise. The formalism is generalizable to multireference spaces which are parts of a CAS. A few test applications of the simplest variant developed in this paper illustrate its potentialities.
1,338 citations
Vilnius University1, University of Ferrara2, Aarhus University3, University of Oslo4, Royal Institute of Technology5, Electromagnetic Geoservices6, University of Trieste7, Norwegian Computing Center8, University of Southern Denmark9, University of Santiago de Compostela10, Danske Bank11, Ruhr University Bochum12, Norwegian Meteorological Institute13, Norwegian Defence Research Establishment14, University of Auckland15, Norwegian University of Science and Technology16, Information Technology University17, Technical University of Ostrava18, Linköping University19, Karlsruhe Institute of Technology20, ETH Zurich21, Australian National University22, University of Modena and Reggio Emilia23, Cisco Systems, Inc.24, University of Buenos Aires25, University of Copenhagen26, University of Erlangen-Nuremberg27, Kazimierz Wielki University in Bydgoszcz28, National Scientific and Technical Research Council29, University of Valencia30, Paul Sabatier University31, University of Melbourne32, University of Nottingham33, University of Bristol34, CLC bio35, Princeton University36, La Trobe University37, Clemson University38
TL;DR: Dalton is a powerful general‐purpose program system for the study of molecular electronic structure at the Hartree–Fock, Kohn–Sham, multiconfigurational self‐consistent‐field, Møller–Plesset, configuration‐interaction, and coupled‐cluster levels of theory.
Abstract: Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, MOller-Plesset, confi ...
1,212 citations
TL;DR: In this article, the n-electron valence state perturbation theory is reformulated in a spin-free formalism, concentrating on the "strongly contracted" and "partially contracted" variants.
Abstract: The n-electron valence state perturbation theory is reformulated in a spin-free formalism, concentrating on the “strongly contracted” and “partially contracted” variants. The new formulation is based on the introduction of average values in the unperturbed state of excitation operators which bear resemblance with analogous ones occurring in the extended Koopmans’ theorem and in the equations-of-motion technique. Such auxiliary quantities, which allow the second-order perturbation contribution to the energy to be evaluated very efficiently, can be calculated at the outset provided the unperturbed four-particle spinless density matrix in the active orbital space is available. A noticeable inequality concerning second-order energy contributions of the same type between the strongly and partially contracted versions is proven to hold. An example concerning the successful calculation of the potential energy curve for the Cr2 molecule is discussed.
882 citations
TL;DR: In this paper, a strongly contracted variant of the n -electron valence state perturbation theory (SC NEV-PT) which uses Dyall's Hamiltonian to define the zero-order energies is considered.
667 citations
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TL;DR: This paper presents a meta-modelling procedure called "Continuum Methods within MD and MC Simulations 3072", which automates the very labor-intensive and therefore time-heavy and expensive process of integrating discrete and continuous components into a discrete-time model.
Abstract: 6.2.2. Definition of Effective Properties 3064 6.3. Response Properties to Magnetic Fields 3066 6.3.1. Nuclear Shielding 3066 6.3.2. Indirect Spin−Spin Coupling 3067 6.3.3. EPR Parameters 3068 6.4. Properties of Chiral Systems 3069 6.4.1. Electronic Circular Dichroism (ECD) 3069 6.4.2. Optical Rotation (OR) 3069 6.4.3. VCD and VROA 3070 7. Continuum and Discrete Models 3071 7.1. Continuum Methods within MD and MC Simulations 3072
13,286 citations
TL;DR: In this article, a method is presented which utilizes the calculation of the molecular electrostatic potential or the electric field at a discrete number of preselected points to evaluate the environmental effects of a solvent on the properties of a molecular system.
7,618 citations
TL;DR: The cclib platform as discussed by the authors is a platform for the development of package-independent computational chemistry algorithms, which can automatically detect, parse, and convert the extracted information into a standard internal representation.
Abstract: There are now a wide variety of packages for electronic structure calculations, each of which differs in the algorithms implemented and the output format. Many computational chemistry algorithms are only available to users of a particular package despite being generally applicable to the results of calculations by any package. Here we present cclib, a platform for the development of package-independent computational chemistry algorithms. Files from several versions of multiple electronic structure packages are automatically detected, parsed, and the extracted information converted to a standard internal representation. A number of population analysis algorithms have been implemented as a proof of principle. In addition, cclib is currently used as an input filter for two GUI applications that analyze output files: PyMOlyze and GaussSum. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008
4,451 citations
TL;DR: This short update provides an overview of the capabilities that have been added to the ORCA electronic structure package (version 4.0) since publication of the first article in 2012.
Abstract: This short update provides an overview of the capabilities that have been added to the ORCA electronic structure package (version 4.0) since publication of the first article in 2012. WIREs Comput Mol Sci 2018, 8:e1327. doi: 10.1002/wcms.1327
This article is categorized under:
Electronic Structure Theory > Ab Initio Electronic Structure Methods
Electronic Structure Theory > Density Functional Theory
Software > Quantum Chemistry
3,241 citations
TL;DR: Molpro (available at http://www.molpro.net) is a general-purpose quantum chemical program as discussed by the authors, which uses local approximations combined with explicit correlation treatments, highly accurate coupled-cluster calculations are now possible for molecules with up to approximately 100 atoms.
Abstract: Molpro (available at http://www.molpro.net) is a general-purpose quantum chemical program. The original focus was on high-accuracy wave function calculations for small molecules, but using local approximations combined with explicit correlation treatments, highly accurate coupled-cluster calculations are now possible for molecules with up to approximately 100 atoms. Recently, multireference correlation treatments were also made applicable to larger molecules. Furthermore, an efficient implementation of density functional theory is available.
2,999 citations