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1.
Data Brief ; 38: 107366, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34584915

RESUMEN

This scientific data article is related to the research work entitled "Non-Covalent functionalization of Single Walled Carbon Nanotubes with Fe-/Co-porphyrin and Co-phthalocyanine for Field-Effect Transistor Applications" published in "Organic electronics" (10.1016/j.orgel.2021.106212). In this work, we present the data of morphological, chemical and structural analyses of non-covalent functionalization of SWNTs with Co-porphyrin and Co-phthalocyanine. The analyses were performed by Raman spectroscopy, transmission electron microscopy as well as the electrical characterization of CNTFETs. This work is completed by the data of the theoretical calculations performed using Density Functional Theory (DFT).

2.
J Phys Chem A ; 124(51): 10787-10798, 2020 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-33315402

RESUMEN

We investigate the oxidation of silver cyanide AgI(CN)2- in water by the OH radical in order to compare this complex with the free cation Ag+ and to measure the influence of the ligands. High-level ab initio calculations of the model species AgII(CN)2· enable the calibration of molecular simulations and the prediction of the oxidized species: AgII(CN)2(H2O)2· and its absorption spectrum, with an intense band at 292 nm and a weaker one at 390 nm. Pulse radiolysis measurements of the oxidation of AgI(CN)2- by the OH radical in water yields a transient species with a broad, intense band at 290 nm and a weaker band at 410 nm at short times after the pulse and a blue shift of the spectrum at longer times. The prediction of the simulations, that the oxidized complex AgII(CN)2(H2O)2· is formed, is confirmed by thermochemistry. Our calculations also suggest that the formation of the OH-adduct is possible only in very basic solution and that the blue shift observed at long times after the pulse is due to disproportionation of the oxidized complex. We also perform molecular simulations of the oxidation of free Ag+ cations by the OH radical. The results are compared to that of the literature and to the results obtained with the AgI(CN)2- complex.

3.
J Chem Phys ; 146(1): 014707, 2017 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-28063437

RESUMEN

In this paper, we study the friction behavior of molecular liquids with anisotropically strained graphene. Due to the changes of lattice and the potential energy surface, the friction is orientation dependent and can be computed by tensorial Green-Kubo formula. Simple quantitative estimations are also proposed for the zero-time response and agree reasonably well with the molecular dynamics results. From simulations, we can obtain the information of structures, dynamics of the system, and study the influence of strain and molecular shapes on the anisotropy degree. It is found that unilateral strain can increase friction in all directions but the strain direction is privileged. Numerical evidences also show that nonspherical molecules are more sensitive to strain and give rise to more pronounced anisotropy effects.

4.
Phys Chem Chem Phys ; 18(26): 17678-90, 2016 Jun 29.
Artículo en Inglés | MEDLINE | ID: mdl-27306786

RESUMEN

The variational nuclear-motion codes ElVibRot and GENIUSH have been used to compute rotational-vibrational states of the F(-)(H2O) anion and its deuterated isotopologue, F(-)(D2O), employing a full-dimensional, semiglobal potential energy surface (PES) called SLBCL, developed as part of this study for the ground electronic state of the complex. The PES is determined from all-electron, explicitly correlated coupled-cluster singles, doubles, and connected triples [CCSD(T)-F12a] computations with an atom-centered, fixed-exponent Gaussian basis set of cc-pCVTZ-F12 quality. The SLBCL PES accurately reproduces the two equivalent minima of the complex, the corresponding transition barrier of C2v point-group symmetry, as well as the proton transfer and the dissociation asymptotes towards the products HF + OH(-) and F(-) + H2O, respectively. The code ElVibRot has been updated so that it can use curvilinear internal coordinates corresponding to a reaction path. The variationally computed vibrational energy levels are compared to relevant experimental and previously determined first-principles results. The vibrational states reveal the presence of pronounced anharmonic effects and considerable intermode couplings resulting in strong resonances, involving in particular the HOH bend and the ionic OH stretch motions. Tunneling results in particularly significant splittings for F(-)(H2O); as expected, the splittings are orders of magnitude smaller for the F(-)(D2O) molecule. The rovibrational energy levels reveal that, despite the large-amplitude vibrational motions, the rotations of F(-)(H2O) basically follow rigid-rotor characteristics.

5.
J Phys Chem A ; 119(26): 6897-908, 2015 Jul 02.
Artículo en Inglés | MEDLINE | ID: mdl-26046588

RESUMEN

Global potentials for the interaction between the Ar atom and gold surfaces are investigated and Ar-Au pair potentials suitable for molecular dynamics simulations are derived. Using a periodic plane-wave representation of the electronic wave function, the nonlocal van-der-Waals vdW-DF2 and vdW-OptB86 approaches have been proved to describe better the interaction. These global interaction potentials have been decomposed to produce pair potentials. Then, the pair potentials have been compared with those derived by combining the dispersionless density functional dlDF for the repulsive part with an effective pairwise dispersion interaction. These repulsive potentials have been obtained from the decomposition of the repulsive interaction between the Ar atom and the Au2 and Au4 clusters and the dispersion coefficients have been evaluated by means of ab initio calculations on the Ar+Au2 complex using symmetry adapted perturbation theory. The pair potentials agree very well with those evaluated through periodic vdW-DF2 calculations. For benchmarking purposes, CCSD(T) calculations have also been performed for the ArAu and Ar+Au2 systems using large basis sets and extrapolations to the complete basis set limit. This work highlights that ab initio calculations using very small surface clusters can be used either as an independent cross-check to compare the performance of state-of-the-art vdW-corrected periodic DFT approaches or, directly, to calculate the pair potentials necessary in further molecular dynamics calculations.

6.
Artículo en Inglés | MEDLINE | ID: mdl-25768605

RESUMEN

In this paper, we use molecular dynamics (MD) simulations to study the mean free path distribution of nonequilibrium gases in micronanochannel and to model the Knudsen (Kn) layer effect. It is found that the mean free path is significantly reduced near the wall and rather insensitive to flow types (Poiseuille or Couette). The Cercignani relation between the mean free path and the viscosity is adopted to capture the velocity behavior of the special zone in the framework of the extended Navier-Stokes (NS) equations. MD simulations of flows are carried out at different Kn numbers. Results are then compared with the theoretical model.

7.
J Chem Phys ; 141(3): 034305, 2014 Jul 21.
Artículo en Inglés | MEDLINE | ID: mdl-25053318

RESUMEN

The full dimensional potential energy surfaces of the (2)A' and (2)A'' electronic components of X̃(2)Π SiCCl have been computed using the explicitly correlated coupled cluster method, UCCSD(T)-F12b, combined with a composite approach taking into account basis set incompleteness, core-valence correlation, scalar relativity, and higher order excitations. The spin-orbit and dipole moment surfaces have also been computed ab initio. The ro-vibronic energy levels and absorption spectrum at 5 K have been determined from variational calculations. The influence of each correction on the fundamental frequencies is discussed. An assignment is proposed for bands observed in the LIF experiment of Smith et al. [J. Chem. Phys. 117, 6446 (2002)]. The overall agreement between the experimental and calculated ro-vibronic levels is better than 7 cm(-1) which is comparable with the 10-20 cm(-1) resolution of the emission spectrum.

8.
Artículo en Inglés | MEDLINE | ID: mdl-23767625

RESUMEN

In this paper we examine the anisotropic slip theory for gas flows based on tangential accommodation coefficients and compare it with molecular dynamics (MD) results. A special gas-wall boundary condition is employed within MD simulations to mimic the anisotropic gas-wall collision mechanism. Results from MD simulations with different surface orientations show good agreement with the slip quantification proposed in this work.


Asunto(s)
Gases/química , Modelos Químicos , Modelos Moleculares , Reología/métodos , Simulación por Computador , Fricción , Resistencia al Corte , Viscosidad
9.
J Chem Phys ; 138(10): 104311, 2013 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-23514493

RESUMEN

The potential energy surfaces of both components of the X̃(2)Π electronic ground state of the double Renner-Teller SiCN/SiNC system are calculated using explicitly correlated coupled cluster approach. The SiNC minimum is found to lie at 628 cm(-1) above the SiCN one. The isomerization transition state is found at 7583 cm(-1) on the (2)A' surface and at 7936 cm(-1) on the (2)A(") surface. The cyclic local minimum on surface (2)A' is also reproduced by our potential energy surface and is located at 3901 cm(-1). The calculated potentials are used to simulate rovibrational spectroscopy employing the recently developed EVEREST variational code. It is shown that Renner-Teller interaction (ε = 0.3043 for SiCN and ε = 0.3874 for SiNC) and spin-orbit coupling are both very important for a correct description of the spectroscopy of this system. Comparison with available experimental measurement is reported.

10.
Phys Rev E Stat Nonlin Soft Matter Phys ; 86(5 Pt 1): 051201, 2012 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23214772

RESUMEN

In this paper, we study the influence of platinum (100) surface morphology on the tangential-momentum accommodation coefficient with argon using a molecular dynamics method. The coefficient is computed directly by beaming Ar atoms onto the surfaces and measuring the relative momentum changes. The wall is maintained at a constant temperature and its interaction with the gas atoms is governed by the Kulginov potential. To capture correctly the surface effect of the walls and the atoms' trajectories, the quantum Sutton-Chen multibody potential is employed between the Pt atoms. The effects of wall surface morphology, incident direction, and temperature are considered in this work and provide full information on the gas-wall interaction.


Asunto(s)
Argón/química , Modelos Químicos , Modelos Moleculares , Platino (Metal)/química , Simulación por Computador , Transferencia de Energía , Propiedades de Superficie
11.
J Phys Chem A ; 116(38): 9484-9, 2012 Sep 27.
Artículo en Inglés | MEDLINE | ID: mdl-22946633

RESUMEN

The low-lying electronic states of Be(2)H(2) have been investigated using an ab initio methodology in order to explore the nature of the Be-Be bonding in this tetra-atomic molecule. The donation of two electrons from the antibonding molecular orbital mainly associated with Be(2) to orbitals mainly associated with the 1s of the H atoms is found to be responsible for the strong Be-Be bond in this tetra-atomic molecule compared with the Be(2) diatomic. In addition to the linear form, a cyclic isomer of Be(2)H(2) has been identified at about 1.47 eV above the linear structure. This structure results from an avoided crossing taking place above the lowest dissociation limit giving two BeH fragments. For the linear structure, a six dimensional potential energy surface has been generated and the rovibrational levels have been computed variationally. The fundamental modes obtained are found to be in well agreement with those detected experimentally. For Be(2)H(2) (Be(2)D(2)), the antisymmetric stretching mode ν(3) is computed at 2028.6 (1519.3) cm(-1).

12.
J Chem Theory Comput ; 6(5): 1565-79, 2010 May 11.
Artículo en Inglés | MEDLINE | ID: mdl-26615691

RESUMEN

A new variational methodology for the treatment of the Renner-Teller effect in tetra-atomic molecules has been developed in valence coordinates. The kinetic-energy operator of Bramley et al. [Mol. Phys. 1991, 73, 1183] for any sequentially bonded four-atom molecule, A-B-C-D, in the singlet nondegenerate electronic state has been adapted to the Renner-Teller and spin couplings by modifying the expression of the nuclear angular momentum. The total Schrödinger equation is solved by diagonalizing the Hamiltonian matrix in a three-step contraction scheme. The main advantage of this new theoretical development is the possibility of studying different isotopomers using the same potential-energy surfaces. This procedure has been tested on HCCH(+) and its deuterated derivatives DCCD(+) and DCCH(+). The calculated rovibronic band origins were compared with previous data deduced from the Jacobi coordinates methodology, dimensionality reduced variational treatment, and photoelectron spectra with a good global agreement. Rotational structures for these systems are also tackled.

13.
J Chem Phys ; 129(14): 144304, 2008 Oct 14.
Artículo en Inglés | MEDLINE | ID: mdl-19045144

RESUMEN

The present paper is devoted to a full quantum mechanical study of the intramolecular vibrational energy redistribution in HFCO and DFCO. In contrast to our previous studies [Pasin et al., J. Chem. Phys. 124, 194304 (2006) and 126, 024302 (2007)], the dynamics is now performed in the presence of an external time-dependent field. This more closely reflects the experimental conditions. A six-dimensional dipole surface is computed. The multiconfiguration time-dependent Hartree method is exploited to propagate the corresponding six-dimensional wave packets. Special emphasis is placed on the excitation of the out-of-plane bending vibration and on the dissociation of the molecule. In the case of DFCO, we predict that it is possible to excite the out-of-plane bending mode of vibration and to drive the dissociation to DF+CO with only one laser pulse with a fixed frequency and without excitation of an electronic state.

14.
J Chem Phys ; 129(4): 044313, 2008 Jul 28.
Artículo en Inglés | MEDLINE | ID: mdl-18681652

RESUMEN

Highly correlated ab initio calculations have been performed for an accurate determination of the electronic structure and of the spectroscopy of the low lying electronic states of the ZnF system. Using effective core pseudopotentials and aug-cc-pVQZ basis sets for both atoms, the potential curves, the dipole moment functions, and the transition dipole moments between relevant electronic states have been calculated at the multireference-configuration-interaction level. The spectroscopic constants calculated for the X(2)Sigma(+) ground state are in good agreement with the most recent theoretical and experimental values. It is shown that, besides the X(2)Sigma(+) ground state, the B(2)Sigma(+), the C(2)Pi, and the D(2)Sigma(+) states are bound. The A(2)Pi state, which has been mentioned in previous works, is not bound but its potential presents a shoulder in the Franck-Condon region of the X(2)Sigma(+) ground state. All of the low lying quartet states are found to be repulsive. The absorption transitions from the v=0 level of the X(2)Sigma(+) ground state toward the three bound states have been evaluated and the spectra are presented. The potential energy of the ZnF(-) molecular anion has been determined in the vicinity of its equilibrium geometry and the electronic affinity of ZnF (EA=1.843 eV with the zero energy point correction) has been calculated in agreement with the photoelectron spectroscopy experiments.


Asunto(s)
Electrones , Fluoruros/química , Compuestos de Zinc/química , Absorción , Teoría Cuántica , Sensibilidad y Especificidad , Análisis Espectral
15.
J Chem Phys ; 127(16): 164315, 2007 Oct 28.
Artículo en Inglés | MEDLINE | ID: mdl-17979346

RESUMEN

The present paper is devoted to a full quantum mechanical study of the cis-->trans isomerization of HONO. In contrast to our previous study [Richter et al., J. Chem. Phys. 120, 6072 (2004)], the dynamics is now performed in the presence of an external time-dependent field in order to be closer to experimental conditions. A six-dimensional dipole surface is computed. Using a previously developed potential energy surface [Richter et al., J. Chem. Phys. 120, 1306 (2004)], all eigenstates up to 4000 cm(-1) are calculated. We simulate the dynamics during and after excitation by an electromagnetic pulse whose parameters are chosen to efficiently trigger the isomerization. Our investigations show that there is a selective isomerization pathway.

16.
Phys Chem Chem Phys ; 9(36): 5027-35, 2007 Sep 28.
Artículo en Inglés | MEDLINE | ID: mdl-17851599

RESUMEN

Density functional theory is used to generate local potential energy surfaces in normal coordinates for several chlorine isotopomers of trichlorofluoromethane (CCl(3)F, CFC11). An examination of predicted structures suggested that the PBE0 functional would be suitable. Anharmonic surfaces around the equilibrium geometries are reported, as determined by energies, gradients, and second derivatives. Vibrational levels for fundamentals, overtones and combination bands are reported, as well as harmonic frequencies, anharmonic constants, rotational constants, isotope shifts, and infrared intensities. These are compared with experimental information.

17.
Spectrochim Acta A Mol Biomol Spectrosc ; 58(4): 825-38, 2002 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-11991497

RESUMEN

A new six-dimensional potential energy function (PEF) of ammonia expressed in internal coordinates is determined by fitting to points evaluated by Density Functional Theory with the B97-1 functional. The C3v and D3h structures are treated on an equal footing. The inversion barrier is 1820 cm(-1), which is in very good agreement with the experimental value of 1834 cm(-1). The minimum 'reaction path' is well defined by the analytic function up to 40 degrees for the umbrella angle. Using this PEF, the vibrational levels are calculated variationally using three different methods. The first employs the internal kinetic energy operator developed for ammonia by Handy, Carter and Colwell (Mol. Phys. 96 (1999) 477). The second uses the code MULTIMODE (J. Chem. Phys. 107 (1997) 10458), which involves the kinetic energy operator as expressed in normal coordinates by Watson. The third uses an implementation of the reaction path hamiltonian (J. Chem. Phys. 72 (1980) 99) within the MULTIMODE code. All three approaches give similar energies for the vibrational energies of ammonia, and these agree with experiment to within 15 cm(-1) for the fundamental vibrations.


Asunto(s)
Amoníaco/química , Espectrofotometría Infrarroja/métodos , Algoritmos , Amoníaco/análisis , Fenómenos Químicos , Química Física , Cinética , Programas Informáticos , Vibración
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