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1.
The structures of the perylene molecule in the first excited 11 0B2u state and the band shape (vibrational structure) of its fluorescence and absorption spectra are computed by the parametric
method. A fragmentary approach and the molecular fragments H/1C= with the parameters obtained for acenes and polyenes are
used to form molecular models in the excited state. It is shown that a model that corresponds to the choice of fragments with
the parameters of acenes is the most optimal. The theoretical spectra satisfactorily reproduce both qualitatively and quantitatively,
the basic specific features of the vibrational structure of the experimental spectra. Calculation results show high degree
of transfer of the parameters of the method in a series of related molecules not only for acenes with “linear” arrangement
of the rings (benzene, naphthalene, anthracene, etc.) but also for more complex structures (perylene). It is shown that the
parametric method developed is efficient for predicting the vibronic spectra and the structure of the excited states of complex
molecules.
Translated fromZhurnal Struktumoi Khimii, Vol.40, No. 2, pp. 242–250, March–April, 1999. 相似文献
2.
The parameters of the adiabatic model of the stilbene molecule in the excited state and the vibrational structure of the fluorescence
spectrum are calculated by the parametric method of the theory of vibronic spectra of complex molecules. The first and second
orders of theory are used. The molecular models are constructed by the fragment method. Satisfactory agreement with experiment
is obtained. The parameters of molecular fragments are shown to be highly transferable. The model and the spectrum max be
refined in the second order of theory using only one additional parameter for CCC angles (optimal values were obtained). The
parametric method under discussion makes it possible to predict variations of structural parameters due to excitation and
to calculate the vibrational structure of the electronic spectra of complex molecules, including characteristic variations
of the spectra in series of related molecules (stilbene-di-phenylpolyenes). This method surpasses all previous procedures
(in particular, the correlation method) in completeness and accuracy of results.
Translated fromZhurnal Strukturnoi Khinii, Vol. 41, No. 2, pp. 369–378, March–April, 2000. 相似文献
3.
V. I. Baranov L. A. Gribov V. O. Jenjer D. Yu. Zelentsov 《Journal of Structural Chemistry》1996,37(6):881-888
The absorption and fluorescence spectra of diphenylpolyenes (diphenylbutadiene, diphenylhexatriene, diphenyloctatetraene,
and 1,6-di(4′-methylphenyl)-1,3,5-hexatriene) are calculated by a recently proposed parametric method using the fragmentation
approach for designing molecular models. The parameters of theH>C=molecular fragment (derivatives of the Coulomb and resonance integrals with respect to internal coordinates in the HAO
basis set) obtained in calculation for polyenes were transferred to the molecular models of diphenylpolyenes without changes
(∂He/∂q(0)=0.055 and ∂2He/∂q
k
(0)
∂q
l
(0)
=0.1 au). The theoretical spectra are sufficiently adequate to quantitatively and qualitatively reproduce the main features
of the vibrational structure of the experimental absorption and fluorescence spectra, and the parameters of the models of
the potential surfaces of the excited states of diphenylpolyenes are consistent with the previous estimations. It is shown
that this method allows predictive calculations of the vibronic spectra of complex molecules and the developed parametrization
posesses all needed properties: locality, transferability, invariance to minor changes in electron density, ranking according
to magnitude, small number of parameters for molecular fragments, etc.
K. A. Timiryazev Moscow Agricultural Academy. Translated fromZhurnal Struktumoi Khimii, Vol. 37, No. 6, pp. 1040–1049, November–December, 1996.
Translated by I. Izvekova 相似文献
4.
In the absorption spectra of isocyclically substituted metal porphyrins, the inactive second electron transition produces
a significant effect on the vibrational structure of the fluorescence spectra due to vibronic borrowing of intensitites. These
vibronic interactions involving the second electron level are universal for the spectra of metal porphyrins.
Institute of Molecular and Atomic Physics, Belarus Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 366–369, March–April, 1995.
Translated by L. Smolina 相似文献
5.
The full electronic absorption spectrum of pyridine N-oxide vapor in the near ultraviolet region has been obtained. The vibronic
structure has been analyzed in detail. The four absorption bands, which are observed at 341, 290, 228, and 217 nm, correspond
to four 0–0 vibronic transitions. The spectrum is interpreted in terms of the CNDO/S method. The symmetry of the vibrations
that exhibit activity due to the Herzberg-Teller effect in different electronic states has been studied.
N. G. Chernyshevskii Saratov State University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 345–349, March–April, 1995.
Translated by I. Izvekova 相似文献
6.
This paper deals with the mechanisms of localization of Franck-Condon vibronic coupling of πσ*- or πlπ*-orbital type in a few vibrational modes, (LVM) in excited electronic states of polyatomic molecules. The analysis of vibronic
coupling uses highly symmetric basis sets (for representing MO structures and normal coordinates ξR) as well as simplified models that relate the shift ΔR of the electron potential minima along the normal coordinates to the MO structure and to ξR in the form of analytical expressions. The modes that are active in LVM are determined from the experimental luminescence
spectra. These ideas about approximately high local symmetry of vibronic coupling in benzene fragments as well as the estimates
of ΔR depending on variations in the MO structure explain the experimental results.
L. Ya. Karpov Physicochemical Scientific Research Institute. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 286–291, March–April, 1995.
Translated by L. Smolina 相似文献
7.
A new algorithm for automatic assignment of the resolved vibrational structure of the electronic absorption spectra of diatomic
and polyatomic molecules is suggested.
Translated fromZhurnal Struktumoi Khimii, Vol. 38, No. 2, pp. 363–368, March–April, 1997. 相似文献
8.
The electronic absorption spectrum of pyridine N-oxide vapor in the region of the third electronic transition (43,000-46,000
cm-1) was recorded. The frequencies and intensities of vibronic bands, including the 0–0 band at 43,896 cm-1, were measured An assignment of the frequencies of fundamental vibrations in the third electronically excited state is suggested
The matrices of rotation and shift of normal coordinates due to electronic excitation are calculated, and the vibronic spectrum
of pyridine N-oxide is interpreted on the basis of these matrices.
Translated fromZhurnal Struktumoi Khimii, Vol. 38, No. 2, pp. 357–362, March–April, 1997. 相似文献
9.
Methylthio- (MTE) and bis-methylthioethyne (BMTE) molecules are calculated by the SCF MO method (geometry optimization, basis
set 6–31G*/MP2). The calculated internal rotation barriers of methyl groups are 7.12 kJ/lmole for MTE and 12.86 kJ/mole for
BMTE (both groups are simultaneously rotated). The s-gosh-orientation of the thiomethyl fragments corresponds to a stable
conformation of BMTE. The estimated values of the s-cis- and s-trans-barriers of mutual rotation of SCH3 groups about the axis of the C≡C bond are 13.61 and 12.54 kJ/mole, respectively. Conformationally sensitive MOs and vibration
frequencies are established. An analysis of the experimental IR absorption and Raman spectra and the calculated vibrational
spectrum makes it possible to conclude that in the liquid phase the BMTE molecules also have an s-gosh-conformation.
Translated fromZhumal Strukturnoi Khimii, Vol. 39, No. 4, pp. 602–609, July–August, 1998. 相似文献
10.
G. N. Ten V. V. Nechaev V. I. Berezin V. I. Baranov 《Journal of Structural Chemistry》1997,38(2):268-276
The vibrational structure of the absorption spectra of the first two π-π* singlet transitions of adenine is calculated in
the Franck-Condon approximation including Herzberg-Teller interactions. The effect of excitation-induced changes in molecular
angles on the intensities of the vibrational components is estimated. Structural models of the adenine molecule in the excited
states are constructed. The theoretical and absorption spectra of the first π-π* transition are compared. The results of the
electronic structure calculations of adenine by different CNDO/S methods are discussed.
Translated fromZhumal Struktumoi Khimii, Vol. 38, No. 2, pp. 334–344, March–April, 1997. 相似文献
11.
A semiempirical parametric method for calculating the vibrational structure of the electronic spectra of polyatomic molecules
is developed; the method is based on the adiabatic molecular model and uses a single parametric system for all excited states.
Within the model approach, simplified analytical expressions for potential surface variation during molecular excitation are
derived; the expressions include the principal terms according to the order of magnitude. The first and second derivatives
of Coulomb and resonance one-electron integrals with respect to natural coordinates in a basis set of hybrid atomic orbitals
are used as parameters. It is shown that the parameters possess distinct locality, are transferable in molecular series, and
may be easily ranked according to absolute values; describing a molecular model requires few most significant parameters.
Excitation-induced variations of potential surfaces and absorption spectra of some molecules (butadiene, hexatriene, octatetraene)
are calculated using only two parameters, which are the same for all molecules. The results of calculations are in good agreement
with the experimental data.
Supported by RFFR grant No. 95-03-08808.
V.I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences. Translated fromZhumal Struckturnoi Khimii, Vol. 37, No. 3, pp. 419–431, May–June, 1996. 相似文献
12.
T. G. Burova 《Journal of Structural Chemistry》1995,36(2):271-275
This paper studies the influence of the Herzberg-Teller effect on the intensity distribution in one- and two-photon absorption
and Raman scattering resonance spectra of substituted benzenes. A quantum mechanical analysis of the intensity distribution
in the spectra of phenylacetylene and pyrazine is accomplished using the general approach suggested in [1, 2]. Due to the
inclusion of vibronic coupling in the calculation, one can explain the presence of lines (as well as their combinations and
overtones) arising from one-quantum excitation of nontotally symmetric vibrations. The calculated data are in good agreement
with the experimental data. Significantly, the two-photon absorption spectrum of pyrazine in the region of the1A1g→1B3u long-wave singlet-singlet transition is explained only by the Herzberg-Teller effect.
Saratov State Pedagogical Institute. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 2, pp. 304–309, March–April, 1995.
Translated by L. Smolina 相似文献
13.
L. S. Khaikin O. E. Grikina B. I. Zhilinskii E. A. Zhilinskaya E. G. Baskir R. V. Nepomnyashchii O. A. Fomicheva M. V. Proskurnina 《Russian Chemical Bulletin》1998,47(9):1653-1665
The equilibrium geometric parameters and structures of transition states of internal rotation for the molecules of methyldicyanophospine
MeP(CN)2 and its isocyano analog MeP(NC)2 were calculated by the RHF and MP2 methods with the 6–31G* and 6–31G** basis sets. At the MP2 level, the total energy of cyanide is −35 kcal mol−1 lower than that of isocyanide and the barriers to internal rotation of methyl group for MeP(CN)2 and MeP(NC)2 are 2.2 and 2.7 kcal mol−1, respectively. For both molecules, the one-dimensionalab initio potential functions of internal rotation approximated by a truncated Fourier series were used to determine the frequencies
of torsional transitions by solving direct vibrational problems for a non-rigid model. The Raman spectrum of crystalline MeP(CN)2 was recorded in the range 3500–50 cm−1. The vibrational spectra of this compound were interpreted by scalingab initio force fields calculated by the RHF and MP2 method. The vibrational spectrum of methyldiisocyanophosphine was predicted with
the use of the obtained scale factors.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1703–1714, September, 1998. 相似文献
14.
N. V. Goncharova E. A. Nikitina V. D. Khavryuchenko E. F. Sheka 《Journal of Structural Chemistry》1995,36(1):50-59
This paper deals with computational modeling of structure and properties of the silicon nitride surface zone using combined
computational and real experiments. The computational experiment implies quantum chemical calculations of structure and vibrational
spectra of polyatomic clusters. The real experiment suggests measurement and analysis of vibrational spectra. For quantum
chemical calculations, semiempirical methods (MNDO and AM1) were chosen. In most calculations, the MNDO/H method was preferred
because of the presence of many H-bonds in the surface zone. For verification of calculations, we calculated the structures
and vibrational spectra of water and ammonia molecules and the water-ammonia complex and compared the results with experimental
and ab initio (extended basis) data; MNDO/H proved to be an optimal method giving reliable results.
Russian Peoples' Friendship University. Translated fromZhurnal Strukturnoi Khimii, Vol. 36, No. 1, pp. 58–69, January–February, 1995.
Translated by L. Smolina 相似文献
15.
D. Yu. Zelentsov 《Journal of Structural Chemistry》1997,38(2):195-200
The previously suggested approximate method for calculating the overlap integrals of vibrational wave functions is considerably
improved for the purpose of maximally accurate calculation of excitation-induced mixing of normal coordinates. A general formula
is obtained for all types of overlap integrals as a finite power series of the potential surface shift parameters; the coefficients
are derivatives of the corresponding generating Junctions represented as polynomials of the shift vector elements of the normal
coordinates and the mixing matrix. The spectra of model molecules of decatetraene and tetra- and hexadecaheptaene were calculated
using the expressions derived in this work and a semiempirical parametric method for determination of excitation-induced changes
in the potential surface of molecules. The calculations confirmed the high efficiency of both the parametric method and the
new technique.
Translated fromZhumal Strukturnoi Khimii, Vol. 38, No. 2, pp. 240–247, March–April, 1997. 相似文献
16.
A. B. Trofimov T. É. Moskovskaya E. V. Gromov N. M. Vitkovskaya J. Schirmer 《Journal of Structural Chemistry》2000,41(3):483-494
An effective ab initio approach to core-level electronic spectral studies is discussed. The approach uses polarization propagator
theory in a second-order algebraic diagram construction ADC(2) approximation for calculating the characteristics of electron
transitions; it also uses the linear vibronic model LVM for investigating the vibrational structure of transitions. The core
excitation specialization of ADC(2) is achieved by introducing the core valence separation (CVS) approximation. K-excitation
spectra of CO and N2 molecules are calculated to examine the potential of the approach. The calculated spectra and the available experimental
data are analyzed to characterize the method. A number of additional facts of methodological and practical value are found,
and new transitions are predicted. It is concluded that ADC(2)/CVS/LVM is a promising approach to problem solving in core
level spectroscopy, which requires qualitatively reliable theoretical estimations.
Translated fromZhurnal Strukturnoi Khimii, Vol. 41, No. 3, May–June, 2000, pp. 590-604. 相似文献
17.
P. J. Stephens F. J. Devlin S. Schürch J. Hulliger 《Theoretical chemistry accounts》2008,119(1-3):19-28
The Absolute configuration (AC) of the chiral alkane D3-anti-trans-anti-trans-anti-trans-perhydrotriphenylene (PHTP), 1, is determined by comparison of density functional theory (DFT) calculations of its vibrational circular dichroism (VCD)
and optical rotation (OR) to the experimental VCD and OR of (+)−1, obtained in high enantiomeric excess using chiral gas chromatography. Conformational analysis of 1 demonstrates that the all-chair (CCCC) conformation is the lowest in energy and that other conformations are too high in
energy to be significantly populated at room temperature. The B3PW91/TZ2P calculated IR spectrum of the CCCC conformation
of 1 is in excellent agreement with the experimental IR spectrum, confirming the conformational analysis and demonstrating the
excellent accuracy of the B3PW91 functional and the TZ2P basis set. The B3PW91/TZ2P calculated VCD spectrum of the CCCC conformation
of S-1 is in excellent agreement with the experimental VCD spectrum of (+)−1, unambiguously defining the AC of 1 to be S(+)/R(−). The B3LYP/aug-cc-pVDZ calculated OR of S-1 over the range 589–365 nm has the same sign and dispersion as the experimental OR of (+)−1, further supporting the AC S(+)/R(−). Our results confirm the AC proposed earlier by Farina and Audisio. This study provides
a further demonstration of the excellent accuracy of VCD spectra predicted using Stephens’ equation for vibrational rotational
strengths together with the ab initio DFT methodology, and further documents the utility of VCD spectroscopy in determining
the ACs of chiral molecules. 相似文献
18.
The splitting of the ν(C=O) absorption band (AB) of about 12 cm−1 is found in the IR spectra of diphenylphthalide (DPP) in the crystalline phase and CCl4 solution. In the crystalline phase, this splitting is likely to be caused by the inequivalence of DPP molecules in the crystallographic
cell, while in the solution, by the dimerization of DPP molecules via dipole-dipole and/or hydrogen bonds. A theoretical low-frequency
shift of the ν(C=O) AB for a complex of two DPP molecules (in comparison with a single molecule) is 14 cm−1 in the PBE/3ξ approximation, which is close to the experimentally observed splitting. In two quantum chemical approximations
(B3LYP/6-311G(d,p) (I) and PBE/3ξ (II)) the optimal structure and vibrational spectrum of DPP are calculated. Approximation I better reproduces the intensities,
whereas approximation II better reproduces the IR frequencies of the DPP spectrum. Almost all 48 ABs of the IR spectrum of DPP are assigned to theoretical
normal vibrations (modes). Based on the potential energy distribution over natural coordinates and the visualization of vibrations,
experimental ABs (and the corresponding modes) are assigned to the stretching and bending vibrations of certain bonds in the
DPP molecule. In particular, ABs at 1107 cm−1 and 970 cm−1 are assigned to the ν(-OC-O-) and ν(-C-O-) stretching vibrations, respectively, of the DPP lactonic ring, which differs from
the previously accepted assignment. The results of the interpretation of the DPP spectrum are used to assign a number of ABs
in the IR spectrum of polydiphenylenephthalide (PDP), for which DPP is a model compound. According to the calculations in
approximation II of the vibrational spectrum of a model valence-bonded dimeric molecule, the intense complex AB at 800–870
cm−1 in the IR spectrum of PDP is mainly due to the out-of-plane bending vibrations of C-H bonds in the 1,4-substituted benzene
rings of polymer biphenyl moieties and the bending vibrations of the lactonic ring. 相似文献
19.
Ali Coruh Faruk Yilmaz Busra Sengez Mustafa Kurt Mehmet Cinar Mehmet Karabacak 《Structural chemistry》2011,22(1):45-56
This work presents the synthesis and characterization of a novel compound, 4-(thiophene-3-ylmethoxy)phthalonitrile (TMP).
The spectroscopic properties of the compound were examined by FT-IR, FT-Raman, NMR, and UV techniques. FT-IR and FT-Raman
spectra in solid state were observed in the region 4000–400 cm−1 and 3500–50 cm−1, respectively. The 1H and 13C NMR spectra were recorded in CDCl3 solution. The UV absorption spectrum of the compound that dissolved in THF was recorded in the range of 200–800 nm. The structural
and spectroscopic data of the molecule in the ground state were calculated using density functional theory (DFT) employing
B3LYP exchange correlation and the 6-311++G(d,p) basis set. The vibrational wavenumbers were calculated and scaled values
were compared with experimental FT-IR and FT-Raman spectra. The complete assignments were performed on the basis of the experimental
results and total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method.
Isotropic chemical shifts (13C NMR and 1H NMR) were calculated using the gauge-invariant atomic orbital (GIAO) method. A study on the electronic properties, such
as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The HOMO and LUMO analyses have been used
to elucidate information regarding charge transfer within the molecule. Comparison of the calculated frequencies, NMR chemical
shifts, absorption wavelengths with the experimental values revealed that DFT method produces good results. 相似文献
20.
I. S. Perelygin 《Journal of Structural Chemistry》1997,38(2):218-226
The structure and shape of bands in the Raman vibrational spectra of polar molecules in liquids are analyzed. The possibility
of using these data to examine interactions of molecules as well as their vibrational and orientational dynamics is shown.
Translated from Zhumal Struktumoi Khimii, Vol. 38, No. 2, pp. 270–281, March–April, 1997. 相似文献