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Benedetta Mennucci - One of the best experts on this subject based on the ideXlab platform.
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polarizable Continuum Model
Wiley Interdisciplinary Reviews: Computational Molecular Science, 2012Co-Authors: Benedetta MennucciAbstract:The polarizable Continuum Model (PCM) is a computational method originally formulated 30 years ago but still today it represents one of the most successful examples among Continuum solvation Models. Such a success is mainly because of the continuous improvements, both in terms of computational efficiency and generality, made by all the people involved in the PCM project. The result of these efforts is that nowadays, PCM, with all its different variants, is the default choice in many computational codes to couple a quantum–mechanical (QM) description of a molecular system with a Continuum description of the environment. In this review, a brief presentation of the main methodological and computational aspects of the method will be given together with an analysis of strengths and critical issues of its coupling with different QM methods. Finally, some examples of applications will be presented and discussed to show the potentialities of PCM in describing the effects of environments of increasing complexity. © 2012 John Wiley & Sons, Ltd.
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a variational formulation of the polarizable Continuum Model
Journal of Chemical Physics, 2010Co-Authors: Filippo Lipparini, Eric Cances, Marco Caricato, Benedetta Mennucci, Giovanni Scalmani, Michael J. FrischAbstract:Continuum solvation Models are widely used to accurately estimate solvent effects on energy, structural and spectroscopic properties of complex molecular systems. The polarizable Continuum Model (PCM) is one of the most versatile among the Continuum Models because of the variety of properties that can be computed and the diversity of methods that can be used to describe the solute from molecular mechanics (MM) to sophisticated quantum mechanical (QM) post-self-consistent field methods or even hybrid QM/MM methods. In this contribution, we present a new formulation of PCM in terms of a free energy functional whose variational parameters include the Continuum polarization (represented by the apparent surface charges), the solute’s atomic coordinates and—possibly—its electronic density. The problem of finding the optimized geometry of the (polarized) solute, with the corresponding self-consistent reaction field, is recast as the minimization of this free energy functional, simultaneously with respect to all its variables. The numerous potential applications of this variational formulation of PCM are discussed, including simultaneous optimization of solute’s geometry and polarization charges and extended Lagrangian dynamics. In particular, we describe in details the simultaneous optimization procedure and we include several numerical examples.
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electronic excitation energies in solution at equation of motion ccsd level within a state specific polarizable Continuum Model approach
Journal of Chemical Physics, 2010Co-Authors: Marco Caricato, Gary W Trucks, Benedetta Mennucci, Giovanni Scalmani, Michael J. FrischAbstract:We present a study of excitation energies in solution at the equation of motion coupled cluster singles and doubles (EOM-CCSD) level of theory. The solvent effect is introduced with a state specific polarizable Continuum Model (PCM), where the solute-solvent interaction is specific for the state of interest. Three definitions of the excited state one-particle density matrix (1PDM) are tested in order to gain information for the development of an integrated EOM-CCSD/PCM method. The calculations show the accuracy of this approach for the computation of such property in solution. Solvent shifts between nonpolar and polar solvents are in good agreement with experiment for the test cases. The completely unrelaxed 1PDM is shown to be a balanced choice between computational effort and accuracy for vertical excitation energies, whereas the response of the ground state CCSD amplitudes and of the molecular orbitals is important for other properties, as for instance the dipole moment.
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structures and properties of electronically excited chromophores in solution from the polarizable Continuum Model coupled to the time dependent density functional theory
Journal of Physical Chemistry A, 2009Co-Authors: Benedetta Mennucci, Chiara Cappelli, Roberto Cammi, Ciro A Guido, Jacopo TomasiAbstract:This paper provides an overview of recent research activities concerning the quantum-mechanical description of structures and properties of electronically excited chromophores in solution. The focus of the paper is on a specific approach to include solvent effects, namely the polarizable Continuum Model (PCM). Such a method represents an efficient strategy if coupled to proper quantum-mechanical descriptions such as the time-dependent density functional theory (TDDFT). As a result, the description of molecules in the condensed phase can be extended to excited states still maintaining the computational efficiency and the physical reliability of the ground-state calculations. The most important theoretical and computational aspects of the coupling between PCM and TDDFT are presented and discussed together with an example of application to the study of the low-lying electronic excited states of push-pull chromophores in different solvents.
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geometries and properties of excited states in the gas phase and in solution theory and application of a time dependent density functional theory polarizable Continuum Model
Journal of Chemical Physics, 2006Co-Authors: Giovanni Scalmani, Jacopo Tomasi, Michael J. Frisch, Benedetta Mennucci, Roberto Cammi, Vincenzo BaroneAbstract:In this paper we present the theory and implementation of analytic derivatives of time-dependent density functional theory (TDDFT) excited states energies, both in vacuo and including solvent effects by means of the polarizable Continuum Model. The method is applied to two case studies: p-nitroaniline and 4-(dimethyl)aminobenzonitrile. For both molecules PCM-TDDFT is shown to be successful in supporting the analysis of experimental data with useful insights for a better understanding of photophysical and photochemical pathways in solution.
Michael J. Frisch - One of the best experts on this subject based on the ideXlab platform.
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a variational formulation of the polarizable Continuum Model
Journal of Chemical Physics, 2010Co-Authors: Filippo Lipparini, Eric Cances, Marco Caricato, Benedetta Mennucci, Giovanni Scalmani, Michael J. FrischAbstract:Continuum solvation Models are widely used to accurately estimate solvent effects on energy, structural and spectroscopic properties of complex molecular systems. The polarizable Continuum Model (PCM) is one of the most versatile among the Continuum Models because of the variety of properties that can be computed and the diversity of methods that can be used to describe the solute from molecular mechanics (MM) to sophisticated quantum mechanical (QM) post-self-consistent field methods or even hybrid QM/MM methods. In this contribution, we present a new formulation of PCM in terms of a free energy functional whose variational parameters include the Continuum polarization (represented by the apparent surface charges), the solute’s atomic coordinates and—possibly—its electronic density. The problem of finding the optimized geometry of the (polarized) solute, with the corresponding self-consistent reaction field, is recast as the minimization of this free energy functional, simultaneously with respect to all its variables. The numerous potential applications of this variational formulation of PCM are discussed, including simultaneous optimization of solute’s geometry and polarization charges and extended Lagrangian dynamics. In particular, we describe in details the simultaneous optimization procedure and we include several numerical examples.
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electronic excitation energies in solution at equation of motion ccsd level within a state specific polarizable Continuum Model approach
Journal of Chemical Physics, 2010Co-Authors: Marco Caricato, Gary W Trucks, Benedetta Mennucci, Giovanni Scalmani, Michael J. FrischAbstract:We present a study of excitation energies in solution at the equation of motion coupled cluster singles and doubles (EOM-CCSD) level of theory. The solvent effect is introduced with a state specific polarizable Continuum Model (PCM), where the solute-solvent interaction is specific for the state of interest. Three definitions of the excited state one-particle density matrix (1PDM) are tested in order to gain information for the development of an integrated EOM-CCSD/PCM method. The calculations show the accuracy of this approach for the computation of such property in solution. Solvent shifts between nonpolar and polar solvents are in good agreement with experiment for the test cases. The completely unrelaxed 1PDM is shown to be a balanced choice between computational effort and accuracy for vertical excitation energies, whereas the response of the ground state CCSD amplitudes and of the molecular orbitals is important for other properties, as for instance the dipole moment.
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a state specific polarizable Continuum Model time dependent density functional theory method for excited state calculations in solution
Journal of Chemical Physics, 2006Co-Authors: Roberto Improta, Vincenzo Barone, Giovanni Scalmani, Michael J. FrischAbstract:An effective state specific (SS) Model for the inclusion of solvent effects in time dependent density functional theory (TD-DFT) computations of excited electronic states has been developed and coded in the framework of the so-called polarizable Continuum Model (PCM). Different relaxation time regimes can be treated thus giving access to a number of different spectroscopic properties together with solvent relaxation energies of paramount relevance in electron transfer processes. SS and conventional linear response (LR) Models have been compared for two benchmark systems (coumarin 153 and formaldehyde in different solvents) and in the limiting simple case of a dipolar solute embedded in a spherical cavity. The results point out the complementarity of LR and SS approaches and the advantages of the latter Model especially for polar solvents. The favorable scaling properties of PCM-TD-DFT Models in both SS and LR variants and their availability in effective quantum mechanical codes pave the route for the computation of reliable spectroscopic properties of large molecules of technological and/or biological interest in their natural environments.
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geometries and properties of excited states in the gas phase and in solution theory and application of a time dependent density functional theory polarizable Continuum Model
Journal of Chemical Physics, 2006Co-Authors: Giovanni Scalmani, Jacopo Tomasi, Michael J. Frisch, Benedetta Mennucci, Roberto Cammi, Vincenzo BaroneAbstract:In this paper we present the theory and implementation of analytic derivatives of time-dependent density functional theory (TDDFT) excited states energies, both in vacuo and including solvent effects by means of the polarizable Continuum Model. The method is applied to two case studies: p-nitroaniline and 4-(dimethyl)aminobenzonitrile. For both molecules PCM-TDDFT is shown to be successful in supporting the analysis of experimental data with useful insights for a better understanding of photophysical and photochemical pathways in solution.
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achieving linear scaling computational cost for the polarizable Continuum Model of solvation
Theoretical Chemistry Accounts, 2004Co-Authors: Giovanni Scalmani, Vincenzo Barone, Konstantin N Kudin, Christian Silvio Pomelli, Gustavo E Scuseria, Michael J. FrischAbstract:This work describes a new and low-scaling implementation of the polarizable Continuum Model (PCM) for computing the self-consistent solvent reaction field. The PCM approach is both general and accurate. It is applicable in the framework of both quantum and classical calculations, and also to hybrid quantum/classical methods. In order to further extend the range of applicability of PCM we addressed the problem of its computational cost. The generation of the finite-elements molecular cavity has been reviewed and reimplemented, achieving linear scaling for systems containing up to 500 atoms. Linear scaling behavior has been achieved also for the iterative solution of the PCM equations, by exploiting the fast multipole method (FMM) for computing electrostatic interactions. Numerical results for large (both linear and globular) chemical systems are discussed.
Vincenzo Barone - One of the best experts on this subject based on the ideXlab platform.
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polarizable force fields and polarizable Continuum Model a fluctuating charges pcm approach 1 theory and implementation
Journal of Chemical Theory and Computation, 2011Co-Authors: Filippo Lipparini, Vincenzo BaroneAbstract:We present a combined fluctuating charges-polarizable Continuum Model approach to describe molecules in solution. Both static and dynamic approaches are discussed: analytical first and second derivatives are shown as well as an extended lagrangian for molecular dynamics simluations. In particular, we use the polarizable Continuum Model to provide nonperiodic boundary conditions for molecular dynamics simulations of aqueous solutions. The extended lagrangian method is extensively discussed, with specific reference to the fluctuating charge Model, from a numerical point of view by means of several examples, and a rationalization of the behavior found is presented. Several prototypical applications are shown, especially regarding solvation of ions and polar molecules in water.
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a state specific polarizable Continuum Model time dependent density functional theory method for excited state calculations in solution
Journal of Chemical Physics, 2006Co-Authors: Roberto Improta, Vincenzo Barone, Giovanni Scalmani, Michael J. FrischAbstract:An effective state specific (SS) Model for the inclusion of solvent effects in time dependent density functional theory (TD-DFT) computations of excited electronic states has been developed and coded in the framework of the so-called polarizable Continuum Model (PCM). Different relaxation time regimes can be treated thus giving access to a number of different spectroscopic properties together with solvent relaxation energies of paramount relevance in electron transfer processes. SS and conventional linear response (LR) Models have been compared for two benchmark systems (coumarin 153 and formaldehyde in different solvents) and in the limiting simple case of a dipolar solute embedded in a spherical cavity. The results point out the complementarity of LR and SS approaches and the advantages of the latter Model especially for polar solvents. The favorable scaling properties of PCM-TD-DFT Models in both SS and LR variants and their availability in effective quantum mechanical codes pave the route for the computation of reliable spectroscopic properties of large molecules of technological and/or biological interest in their natural environments.
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geometries and properties of excited states in the gas phase and in solution theory and application of a time dependent density functional theory polarizable Continuum Model
Journal of Chemical Physics, 2006Co-Authors: Giovanni Scalmani, Jacopo Tomasi, Michael J. Frisch, Benedetta Mennucci, Roberto Cammi, Vincenzo BaroneAbstract:In this paper we present the theory and implementation of analytic derivatives of time-dependent density functional theory (TDDFT) excited states energies, both in vacuo and including solvent effects by means of the polarizable Continuum Model. The method is applied to two case studies: p-nitroaniline and 4-(dimethyl)aminobenzonitrile. For both molecules PCM-TDDFT is shown to be successful in supporting the analysis of experimental data with useful insights for a better understanding of photophysical and photochemical pathways in solution.
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achieving linear scaling computational cost for the polarizable Continuum Model of solvation
Theoretical Chemistry Accounts, 2004Co-Authors: Giovanni Scalmani, Vincenzo Barone, Konstantin N Kudin, Christian Silvio Pomelli, Gustavo E Scuseria, Michael J. FrischAbstract:This work describes a new and low-scaling implementation of the polarizable Continuum Model (PCM) for computing the self-consistent solvent reaction field. The PCM approach is both general and accurate. It is applicable in the framework of both quantum and classical calculations, and also to hybrid quantum/classical methods. In order to further extend the range of applicability of PCM we addressed the problem of its computational cost. The generation of the finite-elements molecular cavity has been reviewed and reimplemented, achieving linear scaling for systems containing up to 500 atoms. Linear scaling behavior has been achieved also for the iterative solution of the PCM equations, by exploiting the fast multipole method (FMM) for computing electrostatic interactions. Numerical results for large (both linear and globular) chemical systems are discussed.
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new developments in the polarizable Continuum Model for quantum mechanical and classical calculations on molecules in solution
Journal of Chemical Physics, 2002Co-Authors: Maurizio Cossi, Giovanni Scalmani, Nadia Rega, Vincenzo BaroneAbstract:The polarizable Continuum Model (PCM), used for the calculation of molecular energies, structures, and properties in liquid solution has been deeply revised, in order to extend its range of applications and to improve its accuracy. The main changes effect the definition of solute cavities, of solvation charges and of the PCM operator added to the molecular Hamiltonian, as well as the calculation of energy gradients, to be used in geometry optimizations. The procedure can be equally applied to quantum mechanical and to classical calculations; as shown also with a number of numerical tests, this PCM formulation is very efficient and reliable. It can also be applied to very large solutes, since all the bottlenecks have been eliminated to obtain a procedure whose time and memory requirements scale linearly with solute size. The present procedure can be used to compute solvent effects at a number of different levels of theory on almost all the chemical systems which can be studied in vacuo.
Giovanni Scalmani - One of the best experts on this subject based on the ideXlab platform.
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a variational formulation of the polarizable Continuum Model
Journal of Chemical Physics, 2010Co-Authors: Filippo Lipparini, Eric Cances, Marco Caricato, Benedetta Mennucci, Giovanni Scalmani, Michael J. FrischAbstract:Continuum solvation Models are widely used to accurately estimate solvent effects on energy, structural and spectroscopic properties of complex molecular systems. The polarizable Continuum Model (PCM) is one of the most versatile among the Continuum Models because of the variety of properties that can be computed and the diversity of methods that can be used to describe the solute from molecular mechanics (MM) to sophisticated quantum mechanical (QM) post-self-consistent field methods or even hybrid QM/MM methods. In this contribution, we present a new formulation of PCM in terms of a free energy functional whose variational parameters include the Continuum polarization (represented by the apparent surface charges), the solute’s atomic coordinates and—possibly—its electronic density. The problem of finding the optimized geometry of the (polarized) solute, with the corresponding self-consistent reaction field, is recast as the minimization of this free energy functional, simultaneously with respect to all its variables. The numerous potential applications of this variational formulation of PCM are discussed, including simultaneous optimization of solute’s geometry and polarization charges and extended Lagrangian dynamics. In particular, we describe in details the simultaneous optimization procedure and we include several numerical examples.
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electronic excitation energies in solution at equation of motion ccsd level within a state specific polarizable Continuum Model approach
Journal of Chemical Physics, 2010Co-Authors: Marco Caricato, Gary W Trucks, Benedetta Mennucci, Giovanni Scalmani, Michael J. FrischAbstract:We present a study of excitation energies in solution at the equation of motion coupled cluster singles and doubles (EOM-CCSD) level of theory. The solvent effect is introduced with a state specific polarizable Continuum Model (PCM), where the solute-solvent interaction is specific for the state of interest. Three definitions of the excited state one-particle density matrix (1PDM) are tested in order to gain information for the development of an integrated EOM-CCSD/PCM method. The calculations show the accuracy of this approach for the computation of such property in solution. Solvent shifts between nonpolar and polar solvents are in good agreement with experiment for the test cases. The completely unrelaxed 1PDM is shown to be a balanced choice between computational effort and accuracy for vertical excitation energies, whereas the response of the ground state CCSD amplitudes and of the molecular orbitals is important for other properties, as for instance the dipole moment.
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a state specific polarizable Continuum Model time dependent density functional theory method for excited state calculations in solution
Journal of Chemical Physics, 2006Co-Authors: Roberto Improta, Vincenzo Barone, Giovanni Scalmani, Michael J. FrischAbstract:An effective state specific (SS) Model for the inclusion of solvent effects in time dependent density functional theory (TD-DFT) computations of excited electronic states has been developed and coded in the framework of the so-called polarizable Continuum Model (PCM). Different relaxation time regimes can be treated thus giving access to a number of different spectroscopic properties together with solvent relaxation energies of paramount relevance in electron transfer processes. SS and conventional linear response (LR) Models have been compared for two benchmark systems (coumarin 153 and formaldehyde in different solvents) and in the limiting simple case of a dipolar solute embedded in a spherical cavity. The results point out the complementarity of LR and SS approaches and the advantages of the latter Model especially for polar solvents. The favorable scaling properties of PCM-TD-DFT Models in both SS and LR variants and their availability in effective quantum mechanical codes pave the route for the computation of reliable spectroscopic properties of large molecules of technological and/or biological interest in their natural environments.
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geometries and properties of excited states in the gas phase and in solution theory and application of a time dependent density functional theory polarizable Continuum Model
Journal of Chemical Physics, 2006Co-Authors: Giovanni Scalmani, Jacopo Tomasi, Michael J. Frisch, Benedetta Mennucci, Roberto Cammi, Vincenzo BaroneAbstract:In this paper we present the theory and implementation of analytic derivatives of time-dependent density functional theory (TDDFT) excited states energies, both in vacuo and including solvent effects by means of the polarizable Continuum Model. The method is applied to two case studies: p-nitroaniline and 4-(dimethyl)aminobenzonitrile. For both molecules PCM-TDDFT is shown to be successful in supporting the analysis of experimental data with useful insights for a better understanding of photophysical and photochemical pathways in solution.
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achieving linear scaling computational cost for the polarizable Continuum Model of solvation
Theoretical Chemistry Accounts, 2004Co-Authors: Giovanni Scalmani, Vincenzo Barone, Konstantin N Kudin, Christian Silvio Pomelli, Gustavo E Scuseria, Michael J. FrischAbstract:This work describes a new and low-scaling implementation of the polarizable Continuum Model (PCM) for computing the self-consistent solvent reaction field. The PCM approach is both general and accurate. It is applicable in the framework of both quantum and classical calculations, and also to hybrid quantum/classical methods. In order to further extend the range of applicability of PCM we addressed the problem of its computational cost. The generation of the finite-elements molecular cavity has been reviewed and reimplemented, achieving linear scaling for systems containing up to 500 atoms. Linear scaling behavior has been achieved also for the iterative solution of the PCM equations, by exploiting the fast multipole method (FMM) for computing electrostatic interactions. Numerical results for large (both linear and globular) chemical systems are discussed.
Jacopo Tomasi - One of the best experts on this subject based on the ideXlab platform.
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structures and properties of electronically excited chromophores in solution from the polarizable Continuum Model coupled to the time dependent density functional theory
Journal of Physical Chemistry A, 2009Co-Authors: Benedetta Mennucci, Chiara Cappelli, Roberto Cammi, Ciro A Guido, Jacopo TomasiAbstract:This paper provides an overview of recent research activities concerning the quantum-mechanical description of structures and properties of electronically excited chromophores in solution. The focus of the paper is on a specific approach to include solvent effects, namely the polarizable Continuum Model (PCM). Such a method represents an efficient strategy if coupled to proper quantum-mechanical descriptions such as the time-dependent density functional theory (TDDFT). As a result, the description of molecules in the condensed phase can be extended to excited states still maintaining the computational efficiency and the physical reliability of the ground-state calculations. The most important theoretical and computational aspects of the coupling between PCM and TDDFT are presented and discussed together with an example of application to the study of the low-lying electronic excited states of push-pull chromophores in different solvents.
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geometries and properties of excited states in the gas phase and in solution theory and application of a time dependent density functional theory polarizable Continuum Model
Journal of Chemical Physics, 2006Co-Authors: Giovanni Scalmani, Jacopo Tomasi, Michael J. Frisch, Benedetta Mennucci, Roberto Cammi, Vincenzo BaroneAbstract:In this paper we present the theory and implementation of analytic derivatives of time-dependent density functional theory (TDDFT) excited states energies, both in vacuo and including solvent effects by means of the polarizable Continuum Model. The method is applied to two case studies: p-nitroaniline and 4-(dimethyl)aminobenzonitrile. For both molecules PCM-TDDFT is shown to be successful in supporting the analysis of experimental data with useful insights for a better understanding of photophysical and photochemical pathways in solution.
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polarizable Continuum Model pcm calculations of solvent effects on optical rotations of chiral molecules
Journal of Physical Chemistry A, 2002Co-Authors: Benedetta Mennucci, Jacopo Tomasi, Michael J. Frisch, Roberto Cammi, James R Cheeseman, F J Devlin, S Gabriel, P J StephensAbstract:A new theory of solvent effects on the optical rotations of chiral molecules is presented. The frequency-dependent electric dipole−magnetic dipole polarizability, βαβ(ν), is calculated using density functional theory (DFT). Solvent effects are included using the polarizable Continuum Model (PCM). DFT/PCM calculations of sodium D line specific rotations, [α]D, have been carried out for seven conformationally rigid chiral organic molecules (fenchone, camphor, α-pinene, β-pinene, camphorquinone, verbenone, and methyloxirane) for a diverse set of seven solvents (cyclohexane, carbon tetrachloride, benzene, chloroform, acetone, methanol, and acetonitrile). The predicted variation in [α]D for the solvents cyclohexane, acetone, methanol, and acetonitrile are in excellent agreement with experiment for all seven molecules. For the solvents carbon tetrachloride, benzene, and chloroform, agreement is much poorer. Since only electrostatic solute−solvent interactions are included in the PCM, our results lead to the con...
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nuclear magnetic shieldings in solution gauge invariant atomic orbital calculation using the polarizable Continuum Model
Journal of Chemical Physics, 1999Co-Authors: Roberto Cammi, Benedetta Mennucci, Jacopo TomasiAbstract:We present the gauge invariant atomic orbital (GIAO) calculation of nuclear magnetic shieldings for solvated molecules described within the polarizable Continuum Model (PCM). The performance of the PCM-GIAO approach is tested in a benchmark calculation of isotropic 13C, 15N, and 17O shielding constants for CH3CN and CH3NO2 in vacuo and in water, both at the Hartree–Fock and density functional levels of theory. Various aspects of the calculation of solvent effects on these properties, such as the dependence on the basis set, the electron correlation, and the size of the molecular cavity embedding the solute, are taken into account and discussed. An interpretation of the gas-to-solution shielding variations in terms of a combined action of the solvent reaction field and the shielding polarizabilities is also given.
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A new integral equation formalism for the polarizable Continuum Model: Theoretical background and applications to Isotropic and anisotropic dielectrics
Journal of Chemical Physics, 1997Co-Authors: Eric Cances, Benedetta Mennucci, Jacopo TomasiAbstract:We present a new integral equation formulation of the polarizable Continuum Model (PCM) which allows one to treat in a single approach dielectrics of different nature: standard isotropic liquids, intrinsically anisotropic medialike liquid crystals and solid matrices, or ionic solutions. The present work shows that integral equation methods may be used with success also for the latter cases, which are usually studied with three-dimensional methods, by far less competitive in terms of computational effort. We present the theoretical bases which underlie the method and some numerical tests which show both a complete equivalence with standard PCM versions for isotropic solvents, and a good efficiency for calculations with anisotropic dielectrics.