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1.
Asger Halkier Henrik Koch Poul Jørgensen Ove Christiansen Ida M. Beck Nielsen Trygve Helgaker 《Theoretical chemistry accounts》1997,97(1-4):150-157
A systematic, high-level ab initio investigation of the water dimer has been performed. The oxygen-oxygen bond distance has
been estimated to be around 2.90 ?, about 0.05 ? shorter than the experimentally estimated distance, challenging the accuracy
of the latter. The interaction energy has been obtained at −5.0±0.1 kcal/mol, which compares favourably with the experimentally
estimated value of −5.4±0.7 kcal/mol. The importance of employing basis sets that include diffuse functions in correlated
calculations on hydrogen-bonded systems is confirmed. In correlated calculations on the water dimer and the hydrogen fluoride
dimer, the counterpoise-corrected interaction energies converge considerably slower towards the basis set limit than do the
uncorrected energies, provided that the correlation-consistent basis sets are augmented with diffuse functions.
Received: 12 February 1997 / Accepted: 5 June 1997 相似文献
2.
The diagrammatic Rayleigh-Schr?dinger perturbation theory for the interaction of two closed-shell systems is developed up
to the third order of pertur-bation using orthogonalized orbitals. The interaction energy is expressed by the Rayleigh-Schr?dinger
perturbation expansion. A simple approach for the estimation of basis set superposition error is introduced. The preliminary
calculations of the intermolecular interactions for the He dimer within the augmented cc-pVTZ basis set are compared with
the supermolecular approach, perturbation calculation in biorthogonal basis sets and symmetry adapted perturbation theory
results.
Received: 17 December 1996 / Accepted: 5 November 1997 相似文献
3.
Ab initio calculations were performed to investigate the structure and bonding of the phenol dimer and its cation, especially
the OH stretching frequencies. Some stable structures of the phenol dimer and its cation were obtained at the Hartree–Fock
level and were found to be in agreement with predictions based on spectroscopic investigations. In these dimers the phenol
moieties are bound by a single OH⋯O hydrogen bond. The hydrogen bond is much stronger in the dimer cation than in the neutral
dimer. The calculated binding energy of the phenol dimer in the most stable structure was 6.5–9.9 kcal/mol at various levels
of calculation, compared with the experimental value of 5 kcal/mol or greater. The binding energy of the phenol dimer cation
is more than 3 times (24.1–30.6 kcal/mol) as large as that of the neutral dimer. For the phenol dimer the OH stretching frequency
of the proton-accepting phenol (PAP) is 3652 cm−1 and that of the proton-donating phenol (PDP) is 3516 cm−1; these are in agreement with observed values of 3654 and 3530 cm−1, respectively. For the phenol dimer cation the OH stretching frequency of the PAP is 3616–3618 cm−1 in comparison with an observed value of 3620 ± 3 cm−1. That of the PDP in the dimer cation is calculated to be 2434–2447 cm−1, which is 1210–1223 cm−1 lower than that of the bare phenol. The large reduction in the OH stretching frequency of the PDP in the phenol dimer cation
is attributed to the formation of a stronger hydrogen bond in the cation than in the neutral dimer.
Received: 24 March 2000 / Accepted: 26 April 2000 / Published online: 11 September 2000 相似文献
4.
The previously developed DFT-SAPT approach, which combines symmetry-adapted intermolecular perturbation theory (SAPT) with a density-functional theory (DFT) representation of the monomers, has been implemented by using density fitting of two-electron objects. This approach, termed DF-DFT-SAPT, scales with the fifth power of the molecular size and with the third power upon increase of the basis set size for a given dimer, thus drastically reducing the cost of the conventional DFT-SAPT method. The accuracy of the density fitting approximation has been tested for the ethyne dimer. It has been found that the errors in the interaction energies due to density fitting are below 10(-3) kcal/mol with suitable auxiliary basis sets and thus one or two orders of magnitude smaller than the errors due to the use of a limited atomic orbital basis set. An investigation of three prominent structures of the benzene dimer, namely, the T shaped, parallel displaced, and sandwich geometries, employing basis sets of up to augmented quadruple-zeta quality shows that DF-DFT-SAPT outperforms second-order Moller-Plesset theory (MP2) and gives total interaction energies which are close to the best estimates inferred from combining the results of MP2 and coupled-cluster theory with single, double, and perturbative triple excitations. 相似文献
5.
π–π and CH···N interactions are vital in biological systems. In this study, stacking and hydrogen-bonded interactions in pyrazine
and triazine dimers were investigated by density functional theory combined with symmetry-adapted perturbation theory (DFT-SAPT)
and counterpoise (CP)-corrected supermolecular MP2, SCS-MP2, B3LYP-D and CCSD(T) calculations. All interaction energies were
computed using the optimized structures at the CP-corrected SCS/aug-cc-pVDZ level, which gave 1–2 kJ/mol lower interaction
energies than the ones computed at the MP2 level. For both dimers, doubly hydrogen-bonded and cross-(displaced) stacked orientations
were found to be the lowest energy ones. The reference CCSD(T) calculations favored the former structure in both dimer systems,
whereas MP2 and SCS-MP2 located the latter as the lowest energy isomer. In particular, the former was found to be lower in
energy than the latter by 2.28 and 1.01 kJ/mol at the CCSD(T)/aug-cc-pVDZ level for pyrazine and triazine, respectively. B3LYP-D
produced interaction energies in agreement with the CCSD(T) at the equilibrium geometries, but it overestimates them at the
short range and underestimates at the long intermonomer separations. Furthermore, it tends to give smaller equilibrium distances
compared to the CCSD(T). DFT-SAPT method was in a good agreement with the reference CCSD(T) calculations. This suggests that
DFT-SAPT can be employed to compute the full potential energy surface of these dimers. Moreover, DFT-SAPT calculations showed
that the electrostatic and dispersion contributions are the most important energy components stabilizing these dimers. The
present study aims to show which theoretical method is the most promising one for the investigation of intermolecular interactions
dominated by π–π and CH···N. Therefore, the findings obtained in this study can be used to unravel the structures of nucleic
acid bases and other systems stabilized by π–π and CH···N interactions. 相似文献
6.
LI Quan College of Chemistry Sichuan Normal University Chengdu China 《中国科学B辑(英文版)》2006,49(3):209-213
The study of the intermolecular interactions that drive the solvation of six-membered nitrogenated aromatic rings is of particular importance since they are known to constitute key building blocks of pro- teins and nucleotides[1―5]. The investigation of the 1:1 adduct of these molecules with water will be the first step in the understanding of such interactions. These molecules possess two different proton-acceptor sites: the ring π cloud and the lone pairs of electrons on the nitrogen atoms… 相似文献
7.
Kjaergaard HG Garden AL Chaban GM Gerber RB Matthews DA Stanton JF 《The journal of physical chemistry. A》2008,112(18):4324-4335
We have calculated frequencies and intensities of fundamental and overtone vibrational transitions in water and water dimer with use of different vibrational methods. We have compared results obtained with correlation-corrected vibrational self-consistent-field theory and vibrational second-order perturbation theory both using normal modes and finally with a harmonically coupled anharmonic oscillator local mode model including OH-stretching and HOH-bending local modes. The coupled cluster with singles, doubles, and perturbative triples ab initio method with augmented correlation-consistent triple-zeta Dunning and atomic natural orbital basis sets has been used to obtain the necessary potential energy and dipole moment surfaces. We identify the strengths and weaknesses of these different vibrational approaches and compare our results to the available experimental results. 相似文献
8.
The van der Waals pyrrole dimer is studied using supermolecular and perturbation ab initio treatment with inclusion of correlation
energy. The influence of selected geometry variations on the interaction energy components is investigated. Our calculations
verified the minimum on the potential energy surface deduced from microwave spectra. Its stability is possibly related not
to the extremal values of the selected interaction energy contributions but its physical origin is connected with the delicate
equilibrium between the repulsive and attractive forces. Any structure variation connected with the extremal attraction energy
is more than compensated for by the repulsion energy.
Received: 11 June 1998 / Accepted: 6 October 1998 / Published online: 1 February 1999 相似文献
9.
Wincel H 《Journal of the American Society for Mass Spectrometry》2011,22(9):1570-1576
The thermochemical properties ΔH
o
n
, ΔS
o
n
, and ΔG
o
n
for the hydration of sodiated and potassiated monosaccharides (Ara = arabinose, Xyl = xylose, Rib = ribose, Glc = glucose,
and Gal = galactose) have been experimentally studied in the gas phase at 10 mbar by equilibria measurements using an electrospray
high-pressure mass spectrometer equipped with a pulsed ion beam reaction chamber. The hydration enthalpies for sodiated complexes
were found to be between −46.4 and −57.7 kJ/mol for the first, and −42.7 and −52.3 kJ/mol for the second water molecule. For
potassiated complexes, the water binding enthalpies were similar for all studied systems and varied between −48.5 and −52.7
kJ/mol. The thermochemical values for each system correspond to a mixture of the α and β anomeric forms of monosaccharide
structures involved in their cationized complexes. 相似文献
10.
11.
Anne Milet Cezary Struniewicz Robert Moszynski Paul E. S. Wormer 《Theoretical chemistry accounts》2000,104(3-4):195-198
The nature and importance of nonadditive three-body interactions in the (H2O)2HCl cluster have been studied by the supermolecule coupled-cluster method and by symmetry-adapted perturbation theory (SAPT).
The convergence of the SAPT expansion was tested by comparison with the results obtained from the supermolecule coupled-cluster
calculations including single, double, and noniterative triple excitations [CCSD(T)]. It is shown that the SAPT results reproduce
the converged CCSD(T) results within 3% at worst. The SAPT method has been used to analyze the three-body interactions for
various geometries of the (H2O)2HCl cluster. It is shown that the induction nonadditivity is dominant, but it is partly quenched by the first-order Heitler–London-type
exchange and higher-order exchange–induction/deformation terms. This implies that the classical induction term alone is not
a reliable approximation to the nonadditive energy and that it will be difficult to approximate the three-body potential for
(H2O)2HCl by a simple analytical expression. The three-body energy represents as much as 21–27% of the pair CCSD(T) intermolecular
energy.
Received: 15 September 1999 / Accepted: 3 February 2000 / Published online: 2 May 2000 相似文献
12.
Using established methods based on correlated atomic natural orbitals (ANOs), sets of contracted polarization functions are
derived for use in calculations of atomic and molecular electrical properties (especially electric moments, dipole polarizabilities
and related property hypersurfaces). Through test calculations on Ne, Ar, NH3 and CO2, these polarization functions are shown to reproduce the accuracy of larger basis sets, to incorporate dynamical electron
correlation effects and are economical to use in conjunction with sophisticated electron-correlation treatments. We also show
how triple-zeta polarized ANO and double-zeta polarized ANO basis sets are constructed from these contracted polarization
functions for use in the calculation of reliable zero-point vibrational averages of electrical properties.
Received: 20 December 1999 / Accepted: 15 February 2000 / Published online: 12 May 2000 相似文献
13.
Ab initio self-consistent-field second-order M?ller–Plesset perturbation theory computations including basis set superposition
error and zero-point vibrational energy corrections have been performed on the complexation of benzene with the polar head
of acetylcholine (ACh). The ACh–benzene complex is about 0.5 kcal/mol less stable than the corresponding tetramethylammonium
(TMA)–benzene complex, with a structure a little distorted with respect to the latter. The electronic structure of ACh is
little modified by the ligand. Overall, the replacement of one methyl group of TMA by the acetyl tail of ACh does not affect
strongly the complexation to benzene, as far as the main interaction is concerned.
Received: 1 April 1999 / Accepted: 19 October 1999 / Published online: 14 March 2000 相似文献
14.
Supermolecular interaction energies are analyzed in terms of the symmetry-adapted perturbation theory and operators defining the inaccuracy of the monomer wave functions. The basis set truncation effects are shown to be of first order in the monomer inaccuracy operators. On the contrary, the usual counterpoise correction schemes are of second order in these operators. Recognition of this difference is used to suggest an approach to corrections for basis-set truncation effects. Also earlier claims--that dimer-centered basis sets may lead to interaction energies free of basis-set superposition effects--are shown to be misleading. According to the present study the basis-set truncation contributions, evaluated by means of the symmetry-adapted perturbation theory with monomer-centered basis sets, provide physically and mathematically justified corrections to supermolecular results for interaction energies. 相似文献
15.
Fourth-order M?ller–Plesset (MP4) correlation energies are computed for 28 atoms and simple molecules employing Dunning's
correlation-consistent polarized-valence m-zeta basis sets for m=2, 3, 4, and 5. Extrapolation formulas are used to predict MP4 energies for infinitely large basis sets. It is shown that
both total and partial MP4 correlation energies can be extrapolated to limit values and that the sum of extrapolated partial
MP4 energies equals the extrapolated total MP4 correlation energy within calculational accuracy. Therefore, partial MP4 correlation
energies can be presented in the form of an MP4 spectrum reflecting the relative importance of different correlation effects.
Typical trends in calculated correlation effects for a given class of electron systems are independent of the basis set used.
As first found by Cremer and He [(1996) J Phys Chem 100:6173], one can use MP4 spectra to distinguish between electron systems with well-separated electron pairs and systems
for which electrons cluster in a confined region of atomic or molecular space. MP4 spectra for increasing size of the basis
set reveal that smaller basis set calculations underestimate the importance of three-electron correlation effects for both
classes by overestimating the importance of pair correlation effects. The minimum size of a basis set required for reliable
MP4 calculations is given by a valence triple-zeta polarized basis, which even in the case of anions performs better than
a valence double-zeta basis augmented by diffuse functions.
Received: 14 June 2000 / Accepted: 16 June 2000 / Published online: 24 October 2000 相似文献
16.
The B3LYP and MP2 methods with 6-31G* basis set were used to predict the geometries of N, N-dimethylformamide (DMF) dimer and DMF–aromatic hydrocarbons interaction systems. A total of 10 conformers were obtained with
no imaginary frequencies, respectively. The interaction energies of these binary mixtures have been obtained. The analyses
of chelpg charge distribution and the atoms in molecules theory (AIM) were used to analyze the nature of the interaction.
The results show the presence of hydrogen bonds between DMF and aromatic hydrocarbons. The interaction between DMF and benzonitrile
is the strongest with the interaction energy of −21.58 kJ mol−1 (BSSE corrected), and the intensity order of interactions is DMF–benzonitrile: d2 > DMF–DMF: a2 > DMF–toluene: c1 > DMF–benzene:
b2. 相似文献
17.
18.
Mary C. Salazar José L. Paz Antonio J. Hernández Carlos I Manzanares Eduardo V. Ludeña 《Theoretical chemistry accounts》2001,106(3):218-222
In the present contribution we report a study of the weakly bound van der Waals N2–He molecule in the framework of the supermolecule approach by means of the PWPW and mPW1PW exchange–correlation functionals,
using density functional theory local-spin-optimized atom-centered basis sets complemented with bond functions optimized at
the mPW1PW level of theory. Calculations show that the mPW1PW functional using bond functions gives a realistic representation
of the interaction-energy potentials for this van der Waals dimer, comparable to reference M?ller–Plesset perturbation theory
calculations. In contrast, the PWPW functional is unable to describe the bonding properties of this system and all values
of the bonding properties obtained at different geometries with this functional are considered out-of-scale compared with
the rest of the calculations presented in this study.
Received: 30 October 2000 / Accepted: 3 January 2001 / Published online: 3 April 2001 相似文献
19.
Ulf Ryde Mats H. M. Olsson Björn O. Roos Antonio Carlos Borin 《Theoretical chemistry accounts》2001,105(6):452-462
The accuracy of theoretical calculations on models of the blue copper proteins is investigated using density functional theory
(DFT) Becke's three-parameter hybrid method with the Lee–Yang–Parr correlation functional (B3LYP) and medium-sized basis sets.
Increasing the basis set to triple-zeta quality with f-type functions on all heavy atoms and enlarging the model [up to Cu(imidazole-CH3)2(SC2H5) (CH3SC2H5)0/+] has only a limited influence on geometries and relative energies. Comparative calculations with more accurate wave-function–based
methods (second-order M?ller–Plesset perturbation theory, complete-active-space second-order perturbation theory, coupled-cluster
method, including single and double replacement amplitudes and in addition triple replacement perturbatively) and a variety
of basis sets on smaller models indicate that the DFT/B3LYP approach gives reliable results with only a small basis set dependence,
whereas the former methods strongly depend on the size of the basis sets. The effect of performing the geometry optimizations
in a continuum solvent is quite small, except for the flexible Cu-SMet bond. The results of this study confirm the earlier results that neither the oxidized nor the reduced copper site in the
blue proteins is strained to any significant degree (in energy terms) by the protein surrounding.
Received: 7 July 2000 / Accepted: 17 November 2000 / Published online: 21 March 2001 相似文献
20.
Mathew D. Halls Julia Velkovski H. Bernhard Schlegel 《Theoretical chemistry accounts》2001,105(6):413-421
Scaling factors for obtaining fundamental vibrational frequencies from harmonic frequencies calculated at six of the most
commonly used levels of theory have been determined from regression analysis for the polarized-valence triple-zeta (pVTZ)
Sadlej electric property basis set. The Sadlej harmonic frequency scaling factors for first- and second-row molecules were
derived from a comparison of a total of 900 individual vibrations for 111 molecules with available experimental frequencies.
Overall, the best performers were the hybrid density functional theory (DFT) methods, Becke's three-parameter exchange functional
with the Lee–Yang–Parr fit for the correlation functional (B3-LYP) and Becke's three-parameter exchange functional with Perdew
and Wang's gradient-corrected correlation functional (B3-PW91). The uniform scaling factors for use with the Sadlej pVTZ basis
set are 0.9066, 0.9946, 1.0047, 0.9726, 0.9674 and 0.9649 for Hartree–Fock, the Slater–Dirac exchange functional with the
Vosko–Wilk–Nusair fit for the correlation functional (S-VWN), Becke's gradient-corrected exchange functional with the Lee–Yang–Parr
fit for the correlation functional (B-LYP), B3-LYP, B3-PW91 and second-order M?ller–Plesset theory with frozen core (MP2(fc)),
respectively. In addition to uniform frequency scaling factors, dual scaling factors were determined to improve the agreement
between computed and observed frequencies. The scaling factors for the wavenumber regions below 1800 cm−1 and above 1800 cm−1 are 0.8981 and 0.9097, 1.0216 and 0.9857, 1.0352 and 0.9948, 0.9927 and 0.9659, 0.9873 and 0.9607, 0.9844 and 0.9584 for
Hartree–Fock, S-VWN, B-LYP, B3-LYP, B3-PW91 and MP2(fc), respectively. Hybrid DFT methods along with the Sadlej pVTZ basis
set provides reliable theoretical vibrational spectra in a cost-effective manner.
Received: 22 May 2000 / Accepted: 30 August 2000 / Published online: 28 February 2001 相似文献