Browsing Center for Organic Photonics and Electronics (COPE) by Subject "Ab initio calculations"
Now showing items 1-7 of 7
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Breakdown of the mirror image symmetry in the optical absorption/emission spectra of oligo(para-phenylene)s
(Georgia Institute of TechnologyAmerican Institute of Physics, 2005-01)The absorption and emission spectra of most luminescent, π-conjugated, organic molecules are the mirror image of each other. In some cases, however, this symmetry is severely broken. In the present work, the asymmetry ... -
The diagonal Born-Oppenheimer correction beyond the Hartree-Fock approximation
(Georgia Institute of TechnologyAmerican Institute of Physics, 2003-03)We report on evaluation of the diagonal Born–Oppenheimer correction (DBOC) to the electronic energy with Hartree–Fock (HF) and conventional correlated wave functions for general molecular systems. Convergence of both HF ... -
Effective conjugation and Raman intensities in oligo(para-phenylene)s: A microscopic view from first-principles calculations
(Georgia Institute of TechnologyAmerican Institute of Physics, 2005-03)Electron-phonon coupling in oligo(para-phenylene)s is addressed in terms of the off-resonance Raman intensities of two distinct modes at 1220 and 1280 cm−1. On the basis of Albrecht’s theory, vibrational coupling and Raman ... -
Electronic and vibrational properties of nickel sulfides from first principles
(Georgia Institute of TechnologyAmerican Institute of Physics, 2007-12)We report the results of first-principles calculations (generalized gradient approximation–Perdew Wang 1991) on the electronic and vibrational properties of several nickel sulfides that are observed on Ni-based anodes in ... -
Full configuration interaction potential energy curves for the X-1 Sigma(+)(g), B-1 Delta(g), and B-'1 Sigma(+)(g) states of C-2: A challenge for approximate methods
(Georgia Institute of TechnologyAmerican Institute of Physics, 2004-11)The C₂ molecule exhibits unusual bonding and several low-lying excited electronic states, making the prediction of its potential energy curves a challenging test for quantum chemical methods. We report full configuration ... -
High accuracy ab initio studies of Li-6(+), Li-6(-), and three isomers of Li-6
(Georgia Institute of TechnologyAmerican Institute of Physics, 2005-02)The structures and energetics of Li6+, Li6− and three isomers of Li6 are investigated using the coupled-cluster singles, doubles and perturbative triples [CCSD(T)] method with valence and core-valence correlation consistent ... -
Hybrid correlation models based on active-space partitioning: Seeking accurate O(N ⁵) ab initio methods for bond breaking
(Georgia Institute of TechnologyAmerican Institute of Physics, 2006-08)Møller-Plesset second-order (MP2) perturbation theory remains the least expensive standard ab initio method that includes electron correlation, scaling as O(N ⁵) with the number of molecular orbitals N. Unfortunately, when ...