Gaussian suite of programs

The Gaussian suite of programs webpage http //www.aaussian.com... 

A more general update method, widely used in the Gaussian suite of programs [19], is due to Schlegel [13], In this method, the Hessian in the n-dimensional subspace spaimed by taking differences between the current q... 

In excerpt 3Y, the authors refer to computational results performed with the Gaussian suite of programs, a computational package used to calculate molecular ab initio or semiempirical electronic structure theory. Computational parameters (e.g., the basis set and level of theory) are included in the description. Do not worry if you do not understand the content of excerpt 3Y the language is intended for chemists with a computational or theoretical background. 

Time resolved laser spectroscopy is likely the best method to get kinetic information on transient states. More information can currently be gained from quantum mechanical calculations at relatively high level of theory using the Gaussian Suite of programs (ab initio and density functional theory). 

Exploring chemistry with electronic structure methods, (2nd Ed, Gaussian Inc., 1996) by M. A. Frisch and J. B. Foresman is a simple and step-by-step introduction to ab initio calculations using the GAUSSIAN suite of programs. 

This series presents reviews of ciurent advances in computational methodologies and applications. The first chapter written by R. Cammi, B. Mennucci, and J. Tomasi provides an overview of their developments of the Polarizable Continuum Model (PCM). This approach has been particularly popularized after its implementation into the GAUSSIAN suite of programs. The authors reveal both the theoretical and numerical aspects of the PCM model. Also, promising extensions of the theory are discussed. Among the possible applications, examples concerning the evaluation of molecular-response properties and spectroscopic quantities are provided. 

The last contribution to correlation energy in Eq. (2.40) is fi , defined by Vosko et al. for both closed-shell and open-sheU systems [38] using different expressions [39]. The default option of this term in the Gaussian suite of programs [40] for closed-shell systems is... 

A closely related approach, using the same kind of molecular cavity has been developed by Tomasi et al. (1981). In this model, the multipole expansion is replaced by a numerical computation of the electrostatic potential inside the cavity, due to the polarization of the boundary by the solute. This model also has been improved along the years. It has various versions all known under the acronym of PCM (Canc s et al. 1997) which are implemented in the Gaussian suites of programs, and a closely related model is available in the Jaguar package (Marten et al. 1996 Tannor et al. 1994). 

Several implementations of the PCM-CC theories have been presented. Caricato et al. (2010) have presented an implementation of the PCM-CC analytical gradients for the ground state of molecular solutes within the Gaussian suite of programs (Frisch et al. 2009). Cammi et al. (2010b) have presented an implementation of the PCM-CC and PCM-EOM-CC analytical derivatives methods within the framework of SAC/SACCI methods. We hope that these computational advances can be profitably used to study molecular processes in condensed phase, where both the accuracy of the QM descriptions and the influence of the environment play a critical role, as in photo-ionization processes, electronic transitions, and charge transfer reactions. 

Programs to provide MPDs now available can use single determinant wave functions from calculations produced by the Gaussian suite of programs [16] for molecules, or by Crystal-98 [17] for periodic systems. MPDs can be produced also with correlated wave functions, via a Quantum Monte Carlo program, cf. [10,15], Probabilities can be computed for multi-determinant wave functions [18], but the optimization of Q is not implemented yet. 

All the calculations have been performed with the Gaussian suite of programs [37] at the B3LYP level [38] using the double C basis set 6-31G(d) [39]. As described by Spino et al. [31], methyl-cyclopentadienylcarboxylate can exist in three equilibrium isomers noted la, lb, and Ic but only a combination of the diene with the ester in the 2-position (Ic) and 1 position (lb) could give rise to the Thiele s ester adduct [23]. 2b and the two forms of 2c products are 4.2 and 4.5/4.9 kcal less stable than 2a. It can be noted that the heat of formation is higher for 2a (16.6 kcal) than the one for 2b (12.4 kcal) and 2c (13.9/13.5 kcal). 

All calculations reported in the following sections have been performed with quantum chemical methods easily accessible via the widely used GAUSSIAN suite of programs. See GAUSSIAN 98 [34] and GAUSSIAN 03 [35]. This arsenal includes conventional ab initio methods and density functional theory (DFT) approaches. We wiU not give further details about the structure and predictive capability of these methods here. For the interested reader, extensive presentations of the above classes of methods are clearly presented in standard references [36-39]. 

The geometry optimizations of molecular structures were performed using the semi-empirical PM3 Hamiltonian [67,68] and the B3LYP/6-3 lG(d) method. All stationary points were confirmed to be true minima by evaluation of hessian. In order to speed up HE and DFT calculations, the fast multipole method (EMM) [47, 48, 69] has been used as implemented in Gaussian suite of programs [56]. We also used linear scaling approaches for calculations of nonlinear optical properties as implemented in ADF package [58]. All the properties are expressed in atomic units. Conversion factors can be found elsewhere [28-31],... 

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