Chemical Physics Letters (v.451, #1-3)

Contents (iii-xi).

Sinusoidal projection of oriented chiral molecules in space. Angular distributions of the principal axes of tensor the polarizability are plotted.A new scheme is proposed to uniquely orient molecules of arbitrary symmetry with respect to the laboratory frame by the interaction of a phase-locked superposition of intense, ( ω , 2 ω ) two-color laser fields whose polarization directions cross each other obliquely with the polarizability and hyperpolarizability of molecules. Applicability of the present scheme is demonstrated for l-alanine by deriving theoretically the quasi-stationary states created adiabatically in a long laser pulse. The results show that a sufficiently high degree of 3D orientation can be achieved in the moderate laser-intensity range ( 10 12 – 10 13 W/cm 2 ) when the initial rotational temperature is as low as 10 - 1 K.

A kinetic study of the reaction of atomic hydrogen with iodobenzene by Yide Gao; Kimberly Fessel; Chris McLeod; Paul Marshall (8-13).
Potential energy diagram for H + C6H5I reaction paths, based on QCISD/cc-pVTZ-PP//B3LYP/cc-pVTZ-PP calculations.The rate constant for the reaction of H atoms with phenyl iodide has been measured using the laser flash-photolysis technique with detection of H by resonance fluorescence. The data over 295–907 K are summarized by the expression k  = 1.45 × 10−18T 2.50exp(74/T) cm3  molecule−1  s−1 with a 95% confidence limit for k of ±8%. Ab initio analysis suggests the dominant products are phenyl and hydrogen iodide.

Resonances associated with the double-well potential of the B ″ B state of H2 correlate well with the cross section features.The B ″ B ¯ ← X 1 Σ g + photodissociation cross section of the H2 molecule has been measured and calculated recently by Glass-Maujean and collaborators [M. Glass-Maujean, S. Klumpp, L. Werner, A. Ehresmann, H. Schmoranzer, J. Phys. B: At. Mol. Opt. Phys. 40 (2007) F-19]. The excited state potential presents a double well. The cross section is oscillatory. The structure was explained as due to an extension in the continuum of the series of vibrational levels belonging to the inner or outer wells. It is shown that a dressed molecular picture is an efficient way to calculate this cross section which is derived from the decay rate of the initial state. Part of the structure is correlated with the resonances associated with the outer well of the excited electronic state.

An (e,2e) coincidence study of formic acid monomer and dimer by K.L. Nixon; W.D. Lawrance; D.B. Jones; P. Euripidies; S. Saha; F. Wang; M.J. Brunger (18-24).
(e,2e) Binding energy spectra and supporting calculations are reported for formic acid monomer and dimer.We report asymmetric coplanar (e,2e) spectroscopy binding energy spectra for formic acid monomer and dimer. We believe the dimer investigation represents the first time (e,2e) has been used to study a system involving intermolecular forces. The experimental work is supplemented by density functional theory and outer valence Green’s function calculations to assist the interpretation of the electronic structures. The plane wave impulse approximation in combination with wavefunctions calculated using the B3LYP/TZVP level of theory appear to be appropriate for the monomer, however, this combination fails for the dimer.

Electronic and vibrational excitations are studied in gas phase amino acids by EEL spectroscopy. Structure in (M–H) anions is identified.Excitation of electronic states below 10 eV and resonant vibrational excitation around 2 eV are investigated in gas phase glycine and d-alanine by electron energy loss spectroscopy. Location of singlet states observed between 5 eV and 10 eV is in good agreement with recent calculations. Vibrational excitation concerns mainly the COOH group and CH stretch modes. Structures in (M–H) cross-sections between 1 eV and 2 eV have been revisited. Dips are clearly observed revealing OH stretch excitation, interpreted as cusps due to competition between decay channels of the resonant state. (M–H) anions and vibrational excitation have also been investigated in propanoic acid for comparison.

Multi-reference calculations of nitric oxide dimer by Naoki Taguchi; Yuji Mochizuki; Takeshi Ishikawa; Kiyoshi Tanaka (31-36).
The nitric oxide dimer has a weak N–N bond because of a severe near-degeneracy involving these two orbitals formed by bonding (denoted as σ) and anti-bonding (σ∗) combinations of π∗ orbitals of two NO fragments. Phasing is colored in green and dark amber.The nitric oxide dimer, (NO)2, has been known as an archetype with severe near-degeneracy because of the weak N–N bonding. We thus performed a series of multi-reference calculations of fourth-order coupled pair approximation (MRCPA4) and configuration interaction (MRCI). For the ground state, the molecular structure of cis form was optimized by these calculations. The MRCPA4 geometry was favorably compared with the recent experimental data, indicating the importance of higher excitations. Low-lying singlet excited states were also addressed. Through these calculations, the intrinsic MR character of this system was illustrated.

Delocalisation in conjugated triazene chromophores: Insights from theory by Julien Preat; Catherine Michaux; Alexandre Lewalle; Eric A. Perpète; Denis Jacquemin (37-42).
The structures and electronic spectra of conjugated triazenes are investigated with TD-DFT.The structures and electronic spectra of four conjugated triazenes have been investigated with a combination of the time-dependent density functional theory and the polarisable continuum model. Aside from reproducing the experimental geometries and absorption wavelengths, the proposed theoretical scheme allows (i) to assess the delocalisation of the triazeno pattern (ii) to explain the shape of the experimental absorption bands (iii) to unravel an excited-state switching when using push–pull auxochroms.

Observation of a temperature-dependent transition of a copper-phthalocyanine thin film adsorbed on HOPG by Takashi Kataoka; Hirohiko Fukagawa; Shunsuke Hosoumi; Kohjiro Nebashi; Kazuyuki Sakamoto; Nobuo Ueno (43-47).
A temperature-dependent transition of a copper-phthalocyanine thin film was studied by using metastable-atom electron spectroscopy and ultraviolet photoelectron spectroscopy.We have studied the temperature-dependent electronic states of a copper-phthalocyanine (CuPc) monolayer film adsorbed on a graphite substrate by using metastable-atom electron spectroscopy and ultraviolet photoelectron spectroscopy. The CuPc molecules, which are flat-lying at room temperature, become tilted and condensed at temperatures below 130 K. Taking the temperature-dependent transition reported in the literature into account, we conclude that the transition observed in the present study originates from the change in the correlation between the molecule–substrate and the intermolecular interactions.

Electronic and crystal structures of nanolaminate yttrium aluminum carbide YAl3C3 by Masatomo Yashima; Koichiro Fukuda; Yasunori Tabira; Miyuki Hisamura (48-52).
LUMO electron density of YAl3C3 indicated a nanolaminate structure, which comprises two-dimensional electrically conductive Y and more insulating Al-C layers.Yttrium aluminum carbide (YAl3C3) was investigated by density functional theory (DFT) calculations and Cu Kα1 X-ray powder diffraction analysis to clarify the electronic and structural features responsible for its thermoelectric properties. The experimental electron density distribution from the X-ray data was consistent with the valence electron density distribution from DFT calculations. A narrow band gap was obtained in calculated density of states, which suggested a poor metallic or semi-metallic behavior. Electron density of the lowest unoccupied molecular orbitals indicated that the YAl3C3 has a nanolaminate structure along the c axis, which comprises two-dimensional electrically conductive Y and more insulating Al–C layers.

A novel molecular dynamics methodology, which is based on an integrated ab initio/classical potential using localized basis functions and non-periodic boundary conditions, has been applied to study the microsolvation of the Zn(II) ion in aqueous solution.A novel molecular dynamics methodology, which is based on an integrated ab initio/classical potential using localized basis functions and non-periodic boundary conditions, has been applied to study the microsolvation of the Zn(II) ion in aqueous solution. The metal ion, along with its first solvent shell, was treated at DFT B3LYP level, while the remaining bulk solvent was modeled with an effective TIP3P water model. The solvent structural arrangement around the ion has been analyzed and the characteristic Zn–O distance favourably compared to recent ND, XRD and EXAFS experiments, as well as to sophisticated cluster calculations.

Electronic structure of 1,3,5-trithia-2,4,6-triazapentalenyl on gold by Kai Iketaki; Kaname Kanai; Wataru Fujita; Kunio Awaga; Jun’ya Tsutsumi; Hiroyuki Yoshida; Naoki Sato; Martin Knupfer; Yukio Ouchi; Kazuhiko Seki (58-62).
The adsorption of 1,3,5-trithia-2,4,6-triazapentalenyl on a gold surface has been studied by X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy.The adsorption of 1,3,5-trithia-2,4,6-triazapentalenyl (TTTA) on a gold surface has been studied using X-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) under ultrahigh vacuum conditions. TTTA was deposited onto the gold substrate by gas-phase dosing. XPS and UPS spectra show that TTTA molecules strongly adsorb on the gold surface. In addition, the UPS spectrum of the TTTA monolayer is in good agreement with the gas-phase UPS spectrum of TTTA, which indicates that the molecules adsorb as a radical without electron transfer from the gold substrate.

A novel all optical molecular scale full adder by Olga Kuznetz; Husein Salman; Naser Shakkour; Yoav Eichen; Shammai Speiser (63-67).
An all optical molecular full adder, based on donor and acceptor half adder moieties communicating via an intramolecular EET process.We show, that one molecule can communicate its logic output as input to another molecule. This transfer is achieved as an electronic energy transfer from a donor to an acceptor. We discuss a specific pair, the rhodamine 6G-azulene, for which there is considerable data, but the scheme is general enough to allow a wide choice of D and A pairs. We present results pertaining to a newly synthesized bichromophoric molecule based on this pair, in which a for the first time an all optical full adder is implemented, utilizing two-photon nonlinear optical excitation and intramolecular electronic energy transfer between the two moieties.

A series of TEM images of α-Fe2O3 nanoparticles recorded at 0.5° incremental tilting angle. These particles do not have a closed cage structure.A Letter by Wang et al. reported synthesis of α-Fe2O3 nanoparticles with a closed cage structure. The authors mistook thickness fringes in the transmission electron micrographs (TEM) as evidence for ‘layers’ of ‘a closed cage structure’. We prepared α-Fe2O3 nanoparticles using procedures described by Wang and recorded a series of TEM images of the particles at 0.5° increments in specimen tilt angle. In this Letter, we first explain the origin of thickness fringes, and then present a series of images to prove that these particles do not have a closed cage structure.

The study of Förster resonance energy transfer from PVK to silicon nanoparticles in their composite films.A novel organic–inorganic hybrid composite was prepared from poly(9-vinyl carbazole) (PVK) and silicon nanoparticles (NPs). The optical properties of the composites were characterized by photoluminescence (PL), photoluminescence excitation (PLE), and PL decays. The results indicated that an efficient Förster resonance energy transfer (FRET) took place from PVK (donor) to silicon NPs (acceptor), which was necessary for the optimization of polymer/inorganic NPs hybrid light-emitting diodes.

Anion-doped TiO2 materials having visible light photoactivity were synthesized from a commercially available, molecular titanium precursor containing nitrogen and carbon.Starting with titanium tri-ethanolaminato isopropoxide, a molecular titanium precursor containing nitrogen and carbon, anion-doped TiO2 photocatalysts were synthesized by a simple solvothermal method. Nitric acid was used to control the extent of anion doping and subsequently adjust the photoresponse of anion-doped TiO2 materials. The synthesized materials were characterized by different techniques and were tested in the photocatalytic degradation of methylene blue under visible light illumination. The results indicate that the molecular titanium precursor possesses intrinsic advantages for fabricating anion-doped TiO2 materials as visible light photocatalysts.

Relating structure with morphology: A comparative study of perfect Langmuir–Blodgett multilayers by Smita Mukherjee; Alokmay Datta; Angelo Giglia; Nichole Mahne; Stefano Nannarone (80-87).
Bidentate bridging coordination of metal ion with headgroup plays key role in stacking of defect-free multilayers.Atomic force microscopy and X-ray reflectivity of metal-stearate (MSt) Langmuir–Blodgett films on hydrophilic Silicon (1 0 0), show dramatic reduction in ‘pinhole’ defects when metal M is changed from Cd to Co, along with excellent periodicity in multilayer, with hydrocarbon tails tilted 9.6° from vertical for CoSt (untilted for CdSt). Near edge X-ray absorption fine structure (NEXAFS) and Fourier transform infra-red (FTIR) spectroscopies indicate bidentate bridging metal-carboxylate coordination in CoSt (unidentate in CdSt), underscoring role of headgroup structure in determining morphology. FTIR studies also show increased packing density in CoSt, consistent with increased coverage.

Nanoscale water capillary bridges under deeply negative pressure by Seung Ho Yang; Michael Nosonovsky; Huan Zhang; Koo-Hyun Chung (88-92).
Phase diagram of water showing the metastable liquid state. Stretched capillary bridge acts like a piston inside a sealed tube.Negative Laplace pressure inside water capillary bridges between two bodies contributes to the pull-off adhesion force that can be measured with the atomic force microscope (AFM). We measure the pull-off force between a nanoscale AFM tip and a silicon wafer in air and in ultrahigh vacuum (UHV). The difference gives us the capillary force contribution, which yields the pressure drop when divided by the foundation area of the bridge. We show that the pressure can be deeply negative, down to −160 MPa.

The endohedral Cu@Si10 cluster is predicted to be especially stable.Density functional electronic-structure calculations were performed for Cu@Si n (n  = 9–15) clusters. The lowest-energy endohedral structure and its stability for each Cu@Si n cluster were determined. The encapsulation of Cu within silicon clusters generates stable neutral Cu@Si n clusters. The binding energies and embedding energies of these clusters indicate that they are likely to be chemically stable. The relative cluster stabilities and other thermodynamic properties alternate with cluster size, with an apparent preference existing for clusters with an even number of Si atoms.

The most important features of the phase diagrams of the cuprate high-temperature superconductors follow surprisingly simple chemical trends.I show that for high temperature ceramic cuprates there is a smooth master curve T c max ( 〈 R 〉 ) for the highest superconductive transition temperatures T c’s as a function of the average number 〈R〉 of Pauling resonating bonds/atom in the parent (undoped) insulator. The existence of such an 〈R〉-dependent optimized T c is suggested by analogies with the microscopic theory of optimized molecular glass networks (such as window glass). The chemical model is part of a larger nanoscopically mixed multiphase structural model that also explains the canonical cuprate phase diagrams, as well as recent dynamical fs pump/ps probe optical relaxation experiments.

Experimental and DFT theoretical studies of SERS effect on gold nanowires array by Lisheng Zhang; Yan Fang; Pengxiang Zhang (102-105).
There were two enhanced mechanism which electromagnetic enhancement and charge transfer enhancement on the gold nanowires array by DFT theoretical.Gold nanowires array with diameter from 90 to 110 nm was prepared on AAO template by laser molecular beam epitaxy (LMBE), and surface-enhanced Raman scattering (SERS) spectrum of probe molecules nicotinic acid (NA) were recorded on the gold nanowires array. The Raman and SERS spectrum of NA using DFT-B3PW91 with lanl2dz based on two models were calculated, and compared with the experimental results. It was found the calculated frequencies were in good agreement with experimental values, which indicates that there are two enhanced mechanism which electromagnetic enhancement and charge transfer enhancement, on the gold nanowires array regarding SERS effect.

Pressure induced structural transformations in catalytically active NH4[Eu(SO4)2] studied by light scattering by A. de Andrés; J. Sánchez-Benítez; C. Cascales; N. Snejko; E. Gutiérrez-Puebla; A. Monge (106-110).
Raman phonons and Eu3+ photoluminescence evidence the induction by pressure in NH4[Eu(SO4)2] of two discontinuous structural transformations around 30 and 70 kbar.Light scattering experiments have been performed under hydrostatic pressures up to 90 kbar in NH4[Eu(SO4)2]. This material behaves as an active catalyst and presents a layered structure with two kinds of sulfate groups bonded to Eu3+ ions. Raman phonons related to the SO4 groups as well as Eu3+ photoluminescence spectra evidence the induction by pressure of two discontinuous structural transformations at around 30 and 70 kbar. No signs of pressure induced disorder is detected, on the contrary, the narrower phonons correspond to the 65 kbar phase. At low pressures the structure accommodates mainly through an anisotropic compression along the a-axis perpendicular to the Eu(SO4)2 layers.

Theoretical study on the second hyperpolarizability of open-shell singlet one-dimensional systems with a charged defect by Akihito Takebe; Masayoshi Nakano; Ryohei Kishi; Masahito Nate; Hideaki Takahashi; Takashi Kubo; Kenji Kamada; Koji Ohta; Benoît Champagne; Edith Botek (111-115).
Cationic open-shell singlet linear chain models ( H 3 + and H 5 + ) exhibit negative γ values with significantly larger amplitudes than those of neutral analogues. The amplitudes increase nonlinearly with the average diradical character, while the chain-length dependence is enhanced by increasing the bond-length alternations.The longitudinal static second hyperpolarizability (γ) has been investigated for models ( H 3 + and H 5 + ) open-shell singlet one-dimensional systems bearing a charged defect. Using various ab initio molecular orbital and density functional theory methods, the γ values of these cationic symmetric hydrogen chain models having different bond-length alternations (BLAs) are analyzed as a function of the average diradical character as well as by adopting the summation-over-states scheme. These systems exhibit negative γ values, of which the amplitudes increase nonlinearly with the average diradical character while the chain-length dependence is enhanced by increasing the BLAs. This dependence of γ with the diradical character is mostly dictated by the strong decrease of the excitation energies.

Steady-state and transient-state optical properties of a charge-transfer composite material MO-PPV/SWNTs by Saisai Chu; Wenhui Yi; Shufeng Wang; Fengming Li; Wenke Feng; Qihuang Gong (116-120).
Static and transient researches on MO-PPV/SWNTs reveal ultrafast intermolecular electron-transfer. Slower exciton migration was also observed.Charge-transfer composite material, poly-1-methoxy-4-octoxy-(para-phenelene vinylene) (MO-PPV) wrapped single wall carbon nanotubes (SWNTs), MO-PPV/SWNTs, was synthesized by in situ polymerization. Photophysics properties of MO-PPV/SWNTs were studied by using steady-state spectra, femtosecond fluorescence up-conversion technique, and streak camera. Compared with the pure MO-PPV in solution, fluorescence quenching was observed. Photoinduced electron-transfer from MO-PPV to SWNTs occurs on femtosecond timescale, while photoinduced intermolecular energy-transfer appears at ∼100 ps timescale.

Where is the positive charge of flavylium cations? by Laura Estévez; Ricardo A. Mosquera (121-126).
QTAIM analysis shows that: (i) resonance forms are not suitable for describing the distribution of the total electron density of the flavylium cation, but provide an approximate picture of π-charges; (ii) the most significant resonance form of flavylium and pelargonidin cations are not equivalent.B3LYP/6-31++G(d,p) electron densities for flavylium and pelargonidin cations analyzed with the quantum theory of atoms in molecules indicate that the distribution of the global positive charge is not well represented by the resonance model. Hydrogens display more than 60% of this charge and the C–O–C unit is slightly negative. If resonance structures are interpreted as exclusively due to π-electron densities the most significant for the flavylium cation would be those leaving a positive charge on C2, whereas those leaving a positive charge on C4′ and C7 would be the best descriptors of the π-electron density for the pelargonidin cation.

Vibrational study of calcium salt of pyridine-2-phospho-4-carboxylic acid by Katarzyna Chruszcz-Lipska; Malgorzata Baranska; Leonard M. Proniewicz (127-131).
The synthesis of calcium salt of pyridine-2-phospho-4-carboxylic acid was presented. Metal–ligand interaction was investigated by using vibrational spectroscopy.The synthesis of unknown calcium salt of pyridine-2-phospho-4-carboxylic acid (Ca3L2  · 7H2O) was presented. Interaction between metal and pyridine-2-phospho-4-carboxylic acid was investigated on the basis of the vibrational spectra of the ligand and its salt and confirmed by theoretical simulation (DFT/B3PW91/6-311++G∗∗). It was determined that the molecule of the acid is completely deprotonated and all oxygen atoms from carboxylic and phosphonic groups bind metal ions.

On the optimal contact potential of proteins by Akira R. Kinjo; Sanzo Miyazawa (132-135).
The lower bound for the contact potential of protein structures leads to a native-like potential.We analytically derive the lower bound of the total conformational energy of a protein structure by assuming that the total conformational energy is well approximated by the sum of sequence-dependent pairwise contact energies. The condition for the native structure achieving the lower bound leads to the contact energy matrix that is a scalar multiple of the native contact matrix, i.e., the so-called G o ¯ potential. We also derive spectral relations between contact matrix and energy matrix, and approximations related to one-dimensional protein structures. Implications for protein structure prediction are discussed.

Accelerated stochastic and hybrid methods for spatial simulations of reaction–diffusion systems by Diego Rossinelli; Basil Bayati; Petros Koumoutsakos (136-140).
Analysis of the role of the number of molecules for the Gray–Scott equations solved with a 300 × 300 discretization with F  = 0:04; 0:06; t  = 1000. From left to right the number of molecules per unit of concentration is increased from 100; 1000; 1000; 5000; 10 000, continuum, respectively.Spatial distributions characterize the evolution of reaction–diffusion models of several physical, chemical, and biological systems. We present two novel algorithms for the efficient simulation of these models: Spatial τ -Leaping ( S τ -Leaping), employing a unified acceleration of the stochastic simulation of reaction and diffusion, and Hybrid τ -Leaping ( H τ -Leaping), combining a deterministic diffusion approximation with a τ -Leaping acceleration of the stochastic reactions. The algorithms are validated by solving Fisher’s equation and used to explore the role of the number of particles in pattern formation. The results indicate that the present algorithms have a nearly constant time complexity with respect to the number of events (reaction and diffusion), unlike the exact stochastic simulation algorithm which scales linearly.

Is it possible to freeze solvent molecules at the correlated level?The n → π and π → π vertical electronic transitions of acetone with two and four H2O which correspond to a first solvation shell are considered. By using localized orbitals, and thanks to the MRCI approach which permits to know the wave function, the role of the various solvent molecules is analysed in details. Distinguishing the solvent molecules allows one to consider them at different calculation levels. The methodology is to compare the spectra obtained with four H2O, with two H2O either in the acetone plane or in a perpendicular plane and when they are completely or partly frozen.

Recently proposed protocol for accurate prediction of the thermodynamic parameters of intermolecular interactions has been tested on benchmark database.Recently proposed protocol for accurate (errors within about 1 kcal/mol of experimental data) prediction of the thermodynamic parameters of intermolecular interactions have been tested against other DFT, MP2 and CCSD(T) based methods for complexes including GC and AT DNA base pairs. Newly optimized procedure comprising of two steps proved itself as good compromise between computational demand and chemical accuracy. The first step of proposed protocol involves the counterpoise corrected optimization and calculation of harmonic frequencies at B3LYP/cc-pVTZ level. The second step consists of single point MP2 (cc-pVDZ and cc-pVTZ) calculations and extrapolation to the complete basis set limit.

A simple but accurate approach, is introduced to calculate the coupling matrix element for thermal electron transfer in donor–bridge–acceptor systems. The method is formulated beyond the two-state framework. The electronic coupling is explicitly expressed through energies of relevant adiabatic states and charges on the donor and acceptor.A simple but accurate approach, the charge-on-site scheme, is introduced to calculate coupling matrix elements for electron transfer (ET) in donor–bridge–acceptor (d–b–a) systems. The electronic coupling is explicitly expressed through energies of relevant adiabatic states and charges on the donor and acceptor sites. The method is formulated within two- and multistate models. The proposed scheme can be directly employed in conjunction with any quantum mechanical method providing atomic charges in the ground and excited states. As an illustration, the charge-on-site method is applied to a π stack GAG consisting of three nucleobases.

A numerical methodology to calculate electronic structures of a molecule in electrochemical environment has been developed on the basis of the finite-temperature density functional theory.We present a numerical methodology to calculate electronic structures of a molecule in electrochemical environment. The methodology is based on the finite-temperature density functional theory (FTDFT) and allows us to study electronic properties of a molecule at a fixed chemical potential μ. The approach is applied to a reaction of NO + + e - ⇄ NO in chemical equilibrium. The solvent effect is taken into account by a conductor-like polarizable continuum model (C-PCM). We demonstrate that the method combined with C-PCM (FTDFT/C-PCM) successfully describes the electronic structures of the molecule in electrochemical environment.

Accurate calculation of the pK a of trifluoroacetic acid using high-level ab initio calculations by Mansoor Namazian; Maryam Zakery; Mohammad R. Noorbala; Michelle L. Coote (163-168).
The pK a value of trifluoroacetic acid has been successfully calculated using high-level ab initio methods of G3 and CBS-QB3.The pK a value of trifluoroacetic acid has been successfully calculated using high-level ab initio methods such as G3 and CBS-QB3. Solvation energies have been calculated using CPCM continuum model of solvation at the HF and B3-LYP levels of theory with various basis sets. Excellent agreement with experiment (to within 0.4 pK a units) was obtained using CPCM solvation energies at the B3-LYP/6-31+G(d) level (or larger) in conjunction with CBS-QB3 or G3 gas-phase energies of trifluoroacetic acid and its anion.

We reply to the comment by Dr. Eduard Matito regarding our recent report on a population analysis. The present article makes additional accounts for our theoretical scheme.We reply to the comment by Dr. Eduard Matito regarding our recent report on a population analysis, in which the total dipole moment of a linear molecule is shown to be reproduced exactly by the set of charges.