There has been a long discussion about the reliability of approximate density functionals for atomic anions. It is well known that the extra electron produces a strong self-interaction error, so strong that the extra electron is unbound. Despite this, electron affinities have been calculated using finite basis sets and very good results have been reported by Schaefer and others. We recently sug...

Quantum mechanical calculations of energies, geometries and vibrational wavenumbers of 4-nitroaniline (4NA) were carried out by using Density functional theory (DFT /B3LYP/6-311++G(d,p)/ CC-pvdz / Aug-cc-Pvdz) method. The optimized geometrical parameters obtained by B3LYP method show good agreement with experimental X-ray data. The best level of theory in order to reproduce the experimental wav...

A potential energy surface for the system of a hydroperoxy radical and a water molecule is presented. The surface was sampled using constrained density functional theory optimizations performed at the B3LYP level of theory using a 6-311‡‡G(3df,3pd) basis set. The data points were ®tted to an analytical function based on a common 4-point model for water and a 5-point model for the peroxy radical...

Carbonic anhydrase (CA) is an enzyme that catalyses the reversible hydration of carbon dioxide. There are three broad classes α, β, and γ, of CA, divided into three genetically unrelated families, namely, animal, plant, and bacterial CAs, respectively. The active site of this enzyme contains a zinc atom which is necessary for catalysis. In this study, the catalytic mechanism of β-CA has been in...

We analyze the structural, electronic, and magnetic properties of the europium chalcogenide series EuX (X = O, S, Se, and Te) using density-functional theory (DFT). To describe the localized 4f states of Eu, we utilize the parameter-free PBE0 and HSE hybrid functionals and found a systematic qualitative and quantitative improvement over the conventional local and semilocal functionals. Both hyb...

A new method for relativistically corrected nuclear magnetic resonance ~NMR! chemical shifts is developed by combining the individual gauge for the localized orbital approach for density functional theory with the normalized elimination of a small component using an effective potential. The new method is used for the calculation of the NMR chemical shifts of Mo and W in various molybdenum and t...

In a previous contribution (Mol. Phys. 103, xxxx, 2005), we established the suitability of density functional theory (DFT) for the calculation of molecular anharmonic force fields. In the present work, we have assessed a wide variety of basis sets and exchange-correlation functionals for harmonic and fundamental frequencies, equilibrium and ground-state rotational constants, and thermodynamic f...

The Gibbs energy of reaction of oxidative addition of ammonia to an iridium complex in diethyl ether was calculated by seven density functional methods, in particular B3LYP, PBE, CAMB3LYP, M05, M06, M06-L, and oB97X. The calculated free energies, based on geometry optimization and frequency calculations in both the gas phase and solution, were compared with the experimental result, 1.3 kcal mol...

Pilocarpine is a natural substance with potential application in the treatment of several diseases. In this work Fourier Transform (FT)-Raman spectrum and the Fourier Transform infra red (FT-IR) spectrum of pilocarpine hydrochloride C11H17N2O2 .Cl − were investigated at 300 K. Vibrational wavenumber and wave vector have been predicted using density functional theory (B3LYP) calculations with th...

We present a density functional theory and ab initio (MP2) study of stereoisomer discrimination between the homochiral and heterochiral dimers of the form M(XYYX’)2, where M is a cationic metal (Li+, Ca2+, Zn2+, Cu+, Cu2+) complexing chalcogen-chalcogen bridges (H2O2, H2S2, H2Se2, and their corresponding methyl and dimethyl derivatives). The heterochiral complexes examined were in general found...