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Gaussian Basis Sets (gaussian + basis_set)
Selected AbstractsGaussian Basis Sets for Some Polyatomic Two-Heavy-Atom HydridesCHEMINFORM, Issue 50 2005Jose M. Pires Abstract For Abstract see ChemInform Abstract in Full Text. [source] Structure, magnetizability, and nuclear magnetic shielding tensors of bis-heteropentalenes.JOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 3 2006Abstract The geometry of the heteropentalenes formed by two phosphole units has been determined at the DFT level. The magnetic susceptibility and the nuclear magnetic shielding at the nuclei of these systems have also been calculated using gauge-including atomic orbitals and a large Gaussian basis set to achieve near Hartree,Fock estimates. A comparative study of the various isomers, of their flattened analogs, and of the parent phosphole molecule, shows that the [3,4-c] isomer is the most aromatic system in the set considered, assuming diatropicity and degree of planarity as indicators, even if it is the less stable in terms of total molecular energy. Plots of magnetic field-induced current densities confirm diatropicity of P-containing bis-heteropentalenenes, showing, however, significant differences from the analogous systems with distinct heteroatoms. The maps give evidence of spiral flow nearby CC bonds, compatible with prevalent distortive behavior of , electrons exalted by pyramidalization at P, and competing against the , electron compression, which would favor planar structure. © 2005 Wiley Periodicals, Inc. J Comput Chem 27: 344,351, 2006 [source] Non,Born,Oppenheimer calculations of the ground state of H3INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 14 2007Mauricio Cafiero Abstract We present quantum,mechanical calculations for the ground state of the H3 system performed without the Born-Oppenehimer approximation. In the calculations we use explicitly correlated Gaussian basis functions that explicitly depend on all of the interparticle distances. These basis functions allow us to achieve high accuracy while explicitly describing nucleus,nucleus, nucleus,electron, and electron,electron correlation effects. Gaussian basis sets ranging in size from 85 to 950 functions have been optimized using a gradient-based procedure. The issue of defining and extracting the H3 molecular structure based on the non-BO wave function is also discussed. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source] Restricted and unrestricted Hartree,Fock approaches applied to spherical quantum dots in a magnetic fieldINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 9 2006C. F. Destefani Abstract The Roothaan and Pople,Nesbet approaches for real atoms are adapted to quantum dots in the presence of a magnetic field. Single-particle Gaussian basis sets are constructed, for each dot radius, under the condition of maximum overlap with the exact functions. The chemical potential, charging energy, and total spin expected values are calculated, and we have verified the validity of the quantum dot energy shell structure as well as Hund's rule for electronic occupation at zero magnetic field. At finite field, we have observed the violation of Hund's rule and studied the influence of magnetic field on the closed and open energy shell configurations. We have also compared the present results with those obtained within the LS-coupling scheme for low electronic occupation numbers. We focus only on ground-state properties and consider quantum dots populated up to 40 electrons, constructed by GaAs or InSb nanocrystals. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Efficiency of numerical basis sets for predicting the binding energies of hydrogen bonded complexes: Evidence of small basis set superposition error compared to Gaussian basis setsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 2 2008Yasuji Inada Abstract Binding energies of selected hydrogen bonded complexes have been calculated within the framework of density functional theory (DFT) method to discuss the efficiency of numerical basis sets implemented in the DFT code DMol3 in comparison with Gaussian basis sets. The corrections of basis set superposition error (BSSE) are evaluated by means of counterpoise method. Two kinds of different numerical basis sets in size are examined; the size of the one is comparable to Gaussian double zeta plus polarization function basis set (DNP), and that of the other is comparable to triple zeta plus double polarization functions basis set (TNDP). We have confirmed that the magnitudes of BSSE in these numerical basis sets are comparative to or smaller than those in Gaussian basis sets whose sizes are much larger than the corresponding numerical basis sets; the BSSE corrections in DNP are less than those in the Gaussian 6-311+G(3df,2pd) basis set, and those in TNDP are comparable to those in the substantially large scale Gaussian basis set aug-cc-pVTZ. The differences in counterpoise corrected binding energies between calculated using DNP and calculated using aug-cc-pVTZ are less than 9 kJ/mol for all of the complexes studied in the present work. The present results have shown that the cost effectiveness in the numerical basis sets in DMol3 is superior to that in Gaussian basis sets in terms of accuracy per computational cost. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2008 [source] Newly developed basis sets for density functional calculationsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 2 2005S. Chiodo Abstract Optimized contracted Gaussian basis sets of double-zeta valence polarized (DZVP) quality for first-row transition metals are presented. The DZVP functions were optimized using the PWP86 generalized gradient approximation (GGA) functional and the B3LYP hybrid functional. For a careful analysis of the basis sets performance the transition metal atoms and cations excitation energies were calculated and compared with the experimental ones. The calculated values were also compared with those obtained using the previously available DZVP basis sets developed at the local-density functional level. Because the new basis sets work better than the previous ones, possible reasons of this behavior are analyzed. The newly developed basis sets also provide a good estimation of other atomic properties such as ionization energies. © 2004 Wiley Periodicals, Inc. J Comput Chem 26: 175,183, 2005 [source] | ||||||||||