Pub Date : 2007-11-01DOI: 10.1163/157404007782913200
M. Mestechkin
The matrix form of TDHF theory for HP is summarized and illustrated by π-electronic applications. The description of intermolecular interaction in crystals by means of the Madelung method is given. A technique of the Lorentz tensor calculation is improved and applied to compare with the direct Hartree-Fock computation of various hyperpolarizabilities. A microscopic explanation of SHG by fullerene C60 is presented. The possibility of SHG by finite length carbon nanotubes is discussed.
{"title":"Hartree-Fock Calculations of Optical Hyperpolarizability of Molecules, Fullerenes, and Carbon Nanotubes Interacting With Ionic Crystal Surface","authors":"M. Mestechkin","doi":"10.1163/157404007782913200","DOIUrl":"https://doi.org/10.1163/157404007782913200","url":null,"abstract":"The matrix form of TDHF theory for HP is summarized and illustrated by π-electronic applications. The description of intermolecular interaction in crystals by means of the Madelung method is given. A technique of the Lorentz tensor calculation is improved and applied to compare with the direct Hartree-Fock computation of various hyperpolarizabilities. A microscopic explanation of SHG by fullerene C60 is presented. The possibility of SHG by finite length carbon nanotubes is discussed.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73279769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-01DOI: 10.1163/157404007782913435
B. Champagne, T. Kubo, Hideaki Takahashi, M. Nakano, A. Takebe, Masahito Nate, E. Botek, K. Kamada, R. Kishi, K. Ohta
We report a study on the static second hyperpolarizabilities (γ) of zethrenes using the UBHandHLYP hybrid density functional theory method. Though zethrenes were originally considered as closed-shell systems, the values of their diradical characters, calculated from the occupation numbers of spin-unrestricted Hartree-Fock natural orbitals (UNOs), demonstrate an open-shell diradical nature, which increases with the size of the middle ring region because of the recovery of the aromaticity in that region. As references, we examine also the γ values of tetrabenzopolyacenes, which are regarded as the corresponding closed-shell systems due to their negligible diradical characters. It is found that the longitudinal γ values for zethrenes are much larger than those of the corresponding reference closed-shell systems, whereas their ratio, γ(zethrene)/γ(reference), is reduced when increasing the length of middle ring regions, i.e., when increasing the diradical character.
{"title":"Second Hyperpolarizability of Zethrenes","authors":"B. Champagne, T. Kubo, Hideaki Takahashi, M. Nakano, A. Takebe, Masahito Nate, E. Botek, K. Kamada, R. Kishi, K. Ohta","doi":"10.1163/157404007782913435","DOIUrl":"https://doi.org/10.1163/157404007782913435","url":null,"abstract":"We report a study on the static second hyperpolarizabilities (γ) of zethrenes using the UBHandHLYP hybrid density functional theory method. Though zethrenes were originally considered as closed-shell systems, the values of their diradical characters, calculated from the occupation numbers of spin-unrestricted Hartree-Fock natural orbitals (UNOs), demonstrate an open-shell diradical nature, which increases with the size of the middle ring region because of the recovery of the aromaticity in that region. As references, we examine also the γ values of tetrabenzopolyacenes, which are regarded as the corresponding closed-shell systems due to their negligible diradical characters. It is found that the longitudinal γ values for zethrenes are much larger than those of the corresponding reference closed-shell systems, whereas their ratio, γ(zethrene)/γ(reference), is reduced when increasing the length of middle ring regions, i.e., when increasing the diradical character.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74955960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-01DOI: 10.1163/157404007782913264
M. Papadopoulos, G. Maroulis, B. Champagne
{"title":"Electric and Magnetic Properties of Atoms and Molecules: A special issue in honour of Professor A.D.Buckingham","authors":"M. Papadopoulos, G. Maroulis, B. Champagne","doi":"10.1163/157404007782913264","DOIUrl":"https://doi.org/10.1163/157404007782913264","url":null,"abstract":"","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78944590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-01DOI: 10.1163/157404007782913282
M. Buldakov, V. Cherepanov, Nataliya S. Nagornova
An analytical method to describe tensor components of the dynamic electronic polarizability αii(R,ω) of diatomic molecules as a function of internuclear distance R and the frequency ω of external electromagnetic field is proposed. The method is based on calculations of upper and lower bounds for αii(R,ω). The bounds are calculated using the known functions of static polarizability αii(R,0) of a molecule, the limited number of energy levels Em(R) of its excited electronic states, and the electric dipole transition moments (di)0m(R). The method has been applied to calculate the dynamic electronic polarizability of H2 molecule over wide ranges of R and ω values.
{"title":"Dynamic Polarizability Functions of the Hydrogen Molecule","authors":"M. Buldakov, V. Cherepanov, Nataliya S. Nagornova","doi":"10.1163/157404007782913282","DOIUrl":"https://doi.org/10.1163/157404007782913282","url":null,"abstract":"An analytical method to describe tensor components of the dynamic electronic polarizability αii(R,ω) of diatomic molecules as a function of internuclear distance R and the frequency ω of external electromagnetic field is proposed. The method is based on calculations of upper and lower bounds for αii(R,ω). The bounds are calculated using the known functions of static polarizability αii(R,0) of a molecule, the limited number of energy levels Em(R) of its excited electronic states, and the electric dipole transition moments (di)0m(R). The method has been applied to calculate the dynamic electronic polarizability of H2 molecule over wide ranges of R and ω values.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78763556","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-01DOI: 10.1163/157404007782913183
M. Balakina
The model suggested earlier by the author and allowing to describe the effect of locally anisotropic polarizable polymer matrix on the nonlinear optical response of incorporated chromophore is generalized to the case when a chromophore charge distribution is approximated by the multipole expansion including the terms up to octupole. The analytical formula for the local electric field, affecting the chromophore in a polymer electret, is obtained as a solution of electrostatic problem for a molecule in an ellipsoidal cavity, with corresponding boundary conditions taken into account. The approach exploits the special cavity ansatz according to which the cavity ellipsoid is chosen to be conformal to the characteristic ellipsoid of the generalized permittivity tensor of the medium. Using a self-consistent procedure, analytical formulas for induced dipole and quadrupole moments and the macroscopic frozen-in polarization are obtained. The relashionship of the microscopic molecular characteristics (electric moments and polarizabilities) with macroscopic electret polarization, as well as with external macroscopic parameters (applied electric field and permittivity of the medium) is established.
{"title":"The Account of Molecular Multipole Moments in the Study of the Effect of Locally Anisotropic Polarizable Deformable Medium on the Nonlinear Optical Response of Incorporated Chromophore","authors":"M. Balakina","doi":"10.1163/157404007782913183","DOIUrl":"https://doi.org/10.1163/157404007782913183","url":null,"abstract":"The model suggested earlier by the author and allowing to describe the effect of locally anisotropic polarizable polymer matrix on the nonlinear optical response of incorporated chromophore is generalized to the case when a chromophore charge distribution is approximated by the multipole expansion including the terms up to octupole. The analytical formula for the local electric field, affecting the chromophore in a polymer electret, is obtained as a solution of electrostatic problem for a molecule in an ellipsoidal cavity, with corresponding boundary conditions taken into account. The approach exploits the special cavity ansatz according to which the cavity ellipsoid is chosen to be conformal to the characteristic ellipsoid of the generalized permittivity tensor of the medium. Using a self-consistent procedure, analytical formulas for induced dipole and quadrupole moments and the macroscopic frozen-in polarization are obtained. The relashionship of the microscopic molecular characteristics (electric moments and polarizabilities) with macroscopic electret polarization, as well as with external macroscopic parameters (applied electric field and permittivity of the medium) is established.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80626602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-01DOI: 10.1163/157404007782913462
B. Skwara, A. Zawada, W. Bartkowiak
Results of many-body analysis of interaction-induced linear and non-linear optical properties are discussed. In particular the size of the basis set superposition error in many-body components of interaction-induced electric properties is examined. In order to eliminate the basis set superposition error the site-site function counterpoise method has been incorporated. The linear fluoroacetylene trimer has been chosen as a model system. In addition the results for two types of geometries (fixed and relaxed one) have been compared in order to determine whether the structural changes influence strongly the components of interaction-induced electric properties.
{"title":"On the Many-Body Components of Interaction-Induced Electric Properties: Linear Fluoroacetylene Trimer as a Case Study.","authors":"B. Skwara, A. Zawada, W. Bartkowiak","doi":"10.1163/157404007782913462","DOIUrl":"https://doi.org/10.1163/157404007782913462","url":null,"abstract":"Results of many-body analysis of interaction-induced linear and non-linear optical properties are discussed. In particular the size of the basis set superposition error in many-body components of interaction-induced electric properties is examined. In order to eliminate the basis set superposition error the site-site function counterpoise method has been incorporated. The linear fluoroacetylene trimer has been chosen as a model system. In addition the results for two types of geometries (fixed and relaxed one) have been compared in order to determine whether the structural changes influence strongly the components of interaction-induced electric properties.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84779402","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-01DOI: 10.1163/157404007782913246
D. Majumdar, J. Leszczynski
State of the art theoretical calculations have been carried out to understand cation-π interactions in different environments. Benzene…ammonium (C6H6…NH4+) and benzene…tetramethylammonium (C6H6…N(CH3)4+) complexes are used as model systems and cation-π interactions in these complexes has been evaluated for their gas phase, partially hydrated and fully solvated (using continuum model) structures. The extent of utility of these model calculations has been discussed in the context of different biological environments.
{"title":"Theoretical Modeling of Cation-π interactions in Various Environments: Case Study Using Benzene…Ammonium and Benzene…Tetramethyl- Ammonium Ion Interactions as Model Systems","authors":"D. Majumdar, J. Leszczynski","doi":"10.1163/157404007782913246","DOIUrl":"https://doi.org/10.1163/157404007782913246","url":null,"abstract":"State of the art theoretical calculations have been carried out to understand cation-π interactions in different environments. Benzene…ammonium (C6H6…NH4+) and benzene…tetramethylammonium (C6H6…N(CH3)4+) complexes are used as model systems and cation-π interactions in these complexes has been evaluated for their gas phase, partially hydrated and fully solvated (using continuum model) structures. The extent of utility of these model calculations has been discussed in the context of different biological environments.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80325365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-01DOI: 10.1163/157404007782913147
S. Pal, A. Datta, S. Pati
The variation in the ground-state dipole moment, polarizability and the 1 st hyperpolarizability for non-chelated porphyrins are studied with increase in the inter-dipolar angles between the pyrrole rings. The different dipolar orientations are realized through twisting of one of the ring along the porphyrin plane. Computations performed on both conformational and configurational isomers of porphyins lead to a variety of structures. For the conformational distortions, the dipole-moment (μ), the polarizability (α) and the 1 st hyperpolarizabilities (β) increase with increase in the distortions. This is understood on the basis of a simple excitonic picture wherein the splitting due to dipolar interactions reduces with increase in the distortions which effectively reduces the optical gap for the system. The computations reveal that dihedral twists within the conventional porphyrin structure provide strategies to design molecules with enhanced linear and nonlinear response functions.
{"title":"Role of Dipolar Interactions in Fine-Tuning the Linear and Nonlinear Optical Responses in Porphyrins","authors":"S. Pal, A. Datta, S. Pati","doi":"10.1163/157404007782913147","DOIUrl":"https://doi.org/10.1163/157404007782913147","url":null,"abstract":"The variation in the ground-state dipole moment, polarizability and the 1 st hyperpolarizability for non-chelated porphyrins are studied with increase in the inter-dipolar angles between the pyrrole rings. The different dipolar orientations are realized through twisting of one of the ring along the porphyrin plane. Computations performed on both conformational and configurational isomers of porphyins lead to a variety of structures. For the conformational distortions, the dipole-moment (μ), the polarizability (α) and the 1 st hyperpolarizabilities (β) increase with increase in the distortions. This is understood on the basis of a simple excitonic picture wherein the splitting due to dipolar interactions reduces with increase in the distortions which effectively reduces the optical gap for the system. The computations reveal that dihedral twists within the conventional porphyrin structure provide strategies to design molecules with enhanced linear and nonlinear response functions.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82794891","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-01DOI: 10.1163/157404007782913156
E. Botek, B. Champagne, P. Gangopadhyay, A. Persoons, T. Verbiest
Using hybrid exchange correlation functional and a basis set including diffuse functions, the Verdet constants of mono-substituted benzenes and oligothiophenes have been evaluated at DFT level using the quadratic response formalism in order to assess the effects of substitution and of chain size on this magneto-optical property. The amplitudes of the Verdet constant are nicely ordered as a function of increasing donor/acceptor character, as estimated using the Hammett's σ parameters, and present substantial exaltation for strong donor groups like the dimethylamino moiety. When available, experimental data supports these conclusions. From calculations on increasingly large oligothiophenes, the Verdet constant appears to evolve almost linearly with the number of thiophene units. Basis set investigations have highlighted the key role of diffuse functions and in particular p and d functions on the C and S atoms.
{"title":"Theoretical Evaluation of the Faraday Effect in Organic Compounds","authors":"E. Botek, B. Champagne, P. Gangopadhyay, A. Persoons, T. Verbiest","doi":"10.1163/157404007782913156","DOIUrl":"https://doi.org/10.1163/157404007782913156","url":null,"abstract":"Using hybrid exchange correlation functional and a basis set including diffuse functions, the Verdet constants of mono-substituted benzenes and oligothiophenes have been evaluated at DFT level using the quadratic response formalism in order to assess the effects of substitution and of chain size on this magneto-optical property. The amplitudes of the Verdet constant are nicely ordered as a function of increasing donor/acceptor character, as estimated using the Hammett's σ parameters, and present substantial exaltation for strong donor groups like the dimethylamino moiety. When available, experimental data supports these conclusions. From calculations on increasingly large oligothiophenes, the Verdet constant appears to evolve almost linearly with the number of thiophene units. Basis set investigations have highlighted the key role of diffuse functions and in particular p and d functions on the C and S atoms.","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73582145","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2007-11-01DOI: 10.1163/157404007782913174
Ping Jin, J. Murray, P. Politzer
The significance of the total molecular electrostatic potential Vtot(r) is well established. However much less attention has been given to its component due to the electrons alone, Vel(r). In this paper, we examine the features of Vel(r) for a group of six molecules, and contrast them to those of Vtot(r). We also assess a proposed relationship between |Vel(r)| and local hardness &eta(r), an index of chemical reactivity. We conclude that it is not generally valid, and that better measures of η(r) are the local ionization energy IS(r) and the inverse of the local polarizability α(r).
{"title":"Electronic Electrostatic Potentials of Molecules, Local Hardness, Local Polarizability and Local Ionization Energy","authors":"Ping Jin, J. Murray, P. Politzer","doi":"10.1163/157404007782913174","DOIUrl":"https://doi.org/10.1163/157404007782913174","url":null,"abstract":"The significance of the total molecular electrostatic potential Vtot(r) is well established. However much less attention has been given to its component due to the electrons alone, Vel(r). In this paper, we examine the features of Vel(r) for a group of six molecules, and contrast them to those of Vtot(r). We also assess a proposed relationship between |Vel(r)| and local hardness &eta(r), an index of chemical reactivity. We conclude that it is not generally valid, and that better measures of η(r) are the local ionization energy IS(r) and the inverse of the local polarizability α(r).","PeriodicalId":101169,"journal":{"name":"Soft Computing Letters","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2007-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89539888","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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