The Experts below are selected from a list of 15009 Experts worldwide ranked by ideXlab platform
Mark R Pederson - One of the best experts on this subject based on the ideXlab platform.
-
a first principles density functional calculation of the electronic and vibrational structure of the key melanin monomers
Journal of Chemical Physics, 2004Co-Authors: Benjamin J Powell, Tunna Baruah, Noam Bernstein, K Brake, Ross H Mckenzie, Paul Meredith, Mark R PedersonAbstract:We report first-principles density-functional calculations for hydroquinone (HQ), indolequinone (IQ), and semiquinone (SQ). These molecules are believed to be the basic building blocks of the eumelanins, a class of biomacromolecules with important biological functions (including photoprotection) and with the potential for certain bioengineering applications. We have used the difference of Self-Consistent Fields method to study the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, HL. We show that HL is similar in IQ and SQ, but approximately twice as large in HQ. This may have important implications for our understanding of the observed broadband optical absorption of the eumelanins. The possibility of using this difference in HL to molecularly engineer the electronic properties of eumelanins is discussed. We calculate the infrared and Raman spectra of the three redox forms from first principles. Each of the molecules have significantly different infrared and Raman signatures, and so these spectra could be used in situ to nondestructively identify the monomeric content of macromolecules. It is hoped that this may be a helpful analytical tool in determining the structure of eumelanin macromolecules and hence in helping to determine the structure-property-function relationships that control the behavior of the eumelanins.
-
a first principles density functional calculation of the electronic and vibrational structure of the key melanin monomers
arXiv: Biomolecules, 2004Co-Authors: Benjamin J Powell, Tunna Baruah, Noam Bernstein, K Brake, Ross H Mckenzie, Paul Meredith, Mark R PedersonAbstract:We report first principles density functional calculations for hydroquinone (HQ), indolequinone (IQ) and semiquinone (SQ). These molecules are believed to be the basic building blocks of the eumelanins, a class of bio-macromolecules with important biological functions (including photoprotection) and with potential for certain bioengineering applications. We have used the DeltaSCF (difference of Self Consistent Fields) method to study the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), Delta_HL. We show that Delta_HL is similar in IQ and SQ but approximately twice as large in HQ. This may have important implications for our understanding of the observed broad band optical absorption of the eumelanins. The possibility of using this difference in Delta_HL to molecularly engineer the electronic properties of eumelanins is discussed. We calculate the infrared and Raman spectra of the three redox forms from first principles. Each of the molecules have significantly different infrared and Raman signatures, and so these spectra could be used in situ to non-destructively identify the monomeric content of macromolecules. It is hoped that this may be a helpful analytical tool in determining the structure of eumelanin macromolecules and hence in helping to determine the structure-property-function relationships that control the behaviour of the eumelanins.
Benjamin J Powell - One of the best experts on this subject based on the ideXlab platform.
-
a first principles density functional calculation of the electronic and vibrational structure of the key melanin monomers
Journal of Chemical Physics, 2004Co-Authors: Benjamin J Powell, Tunna Baruah, Noam Bernstein, K Brake, Ross H Mckenzie, Paul Meredith, Mark R PedersonAbstract:We report first-principles density-functional calculations for hydroquinone (HQ), indolequinone (IQ), and semiquinone (SQ). These molecules are believed to be the basic building blocks of the eumelanins, a class of biomacromolecules with important biological functions (including photoprotection) and with the potential for certain bioengineering applications. We have used the difference of Self-Consistent Fields method to study the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, HL. We show that HL is similar in IQ and SQ, but approximately twice as large in HQ. This may have important implications for our understanding of the observed broadband optical absorption of the eumelanins. The possibility of using this difference in HL to molecularly engineer the electronic properties of eumelanins is discussed. We calculate the infrared and Raman spectra of the three redox forms from first principles. Each of the molecules have significantly different infrared and Raman signatures, and so these spectra could be used in situ to nondestructively identify the monomeric content of macromolecules. It is hoped that this may be a helpful analytical tool in determining the structure of eumelanin macromolecules and hence in helping to determine the structure-property-function relationships that control the behavior of the eumelanins.
-
a first principles density functional calculation of the electronic and vibrational structure of the key melanin monomers
arXiv: Biomolecules, 2004Co-Authors: Benjamin J Powell, Tunna Baruah, Noam Bernstein, K Brake, Ross H Mckenzie, Paul Meredith, Mark R PedersonAbstract:We report first principles density functional calculations for hydroquinone (HQ), indolequinone (IQ) and semiquinone (SQ). These molecules are believed to be the basic building blocks of the eumelanins, a class of bio-macromolecules with important biological functions (including photoprotection) and with potential for certain bioengineering applications. We have used the DeltaSCF (difference of Self Consistent Fields) method to study the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), Delta_HL. We show that Delta_HL is similar in IQ and SQ but approximately twice as large in HQ. This may have important implications for our understanding of the observed broad band optical absorption of the eumelanins. The possibility of using this difference in Delta_HL to molecularly engineer the electronic properties of eumelanins is discussed. We calculate the infrared and Raman spectra of the three redox forms from first principles. Each of the molecules have significantly different infrared and Raman signatures, and so these spectra could be used in situ to non-destructively identify the monomeric content of macromolecules. It is hoped that this may be a helpful analytical tool in determining the structure of eumelanin macromolecules and hence in helping to determine the structure-property-function relationships that control the behaviour of the eumelanins.
Donald G Truhlar - One of the best experts on this subject based on the ideXlab platform.
-
density functional calculations of e2 and sn2 reactions effects of the choice of density functional basis set and Self Consistent iterations
Journal of Chemical Theory and Computation, 2010Co-Authors: Yan Zhao, Donald G TruhlarAbstract:We have computed stationary points on the potential energy surface for the anti-E2, syn-E2, and SN2 pathways of the reactions of F− and Cl− with CH3CH2F and CH3CH2Cl with fully Self-Consistent Fields and Gaussian basis functions. We find large differences from previously reported [Bento, A. P.; Sola, M.; Bickelhaupt, F. M. J. Chem. Theory Comput. 2008, 4, 929] calculations with Slater-type orbitals. We revise the findings of the previous study; in particular, we find average absolute errors in kcal/mol compared to benchmark calculations of 20 stationary point energies (6 saddle points and 14 minima) of 0.9 for M06-2X, 1.2 for M08-SO, 1.4 for M06-HF, 2.0 for M06, 2.3 for B3LYP, 2.5 for OLYP, 2.7 for M06-L, and 3.5 kcal/mol for TPSS. We also compare the predictions of various density functionals for the partial atomic charges at the transition states.
Paul Meredith - One of the best experts on this subject based on the ideXlab platform.
-
a first principles density functional calculation of the electronic and vibrational structure of the key melanin monomers
Journal of Chemical Physics, 2004Co-Authors: Benjamin J Powell, Tunna Baruah, Noam Bernstein, K Brake, Ross H Mckenzie, Paul Meredith, Mark R PedersonAbstract:We report first-principles density-functional calculations for hydroquinone (HQ), indolequinone (IQ), and semiquinone (SQ). These molecules are believed to be the basic building blocks of the eumelanins, a class of biomacromolecules with important biological functions (including photoprotection) and with the potential for certain bioengineering applications. We have used the difference of Self-Consistent Fields method to study the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, HL. We show that HL is similar in IQ and SQ, but approximately twice as large in HQ. This may have important implications for our understanding of the observed broadband optical absorption of the eumelanins. The possibility of using this difference in HL to molecularly engineer the electronic properties of eumelanins is discussed. We calculate the infrared and Raman spectra of the three redox forms from first principles. Each of the molecules have significantly different infrared and Raman signatures, and so these spectra could be used in situ to nondestructively identify the monomeric content of macromolecules. It is hoped that this may be a helpful analytical tool in determining the structure of eumelanin macromolecules and hence in helping to determine the structure-property-function relationships that control the behavior of the eumelanins.
-
a first principles density functional calculation of the electronic and vibrational structure of the key melanin monomers
arXiv: Biomolecules, 2004Co-Authors: Benjamin J Powell, Tunna Baruah, Noam Bernstein, K Brake, Ross H Mckenzie, Paul Meredith, Mark R PedersonAbstract:We report first principles density functional calculations for hydroquinone (HQ), indolequinone (IQ) and semiquinone (SQ). These molecules are believed to be the basic building blocks of the eumelanins, a class of bio-macromolecules with important biological functions (including photoprotection) and with potential for certain bioengineering applications. We have used the DeltaSCF (difference of Self Consistent Fields) method to study the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), Delta_HL. We show that Delta_HL is similar in IQ and SQ but approximately twice as large in HQ. This may have important implications for our understanding of the observed broad band optical absorption of the eumelanins. The possibility of using this difference in Delta_HL to molecularly engineer the electronic properties of eumelanins is discussed. We calculate the infrared and Raman spectra of the three redox forms from first principles. Each of the molecules have significantly different infrared and Raman signatures, and so these spectra could be used in situ to non-destructively identify the monomeric content of macromolecules. It is hoped that this may be a helpful analytical tool in determining the structure of eumelanin macromolecules and hence in helping to determine the structure-property-function relationships that control the behaviour of the eumelanins.
K Brake - One of the best experts on this subject based on the ideXlab platform.
-
a first principles density functional calculation of the electronic and vibrational structure of the key melanin monomers
Journal of Chemical Physics, 2004Co-Authors: Benjamin J Powell, Tunna Baruah, Noam Bernstein, K Brake, Ross H Mckenzie, Paul Meredith, Mark R PedersonAbstract:We report first-principles density-functional calculations for hydroquinone (HQ), indolequinone (IQ), and semiquinone (SQ). These molecules are believed to be the basic building blocks of the eumelanins, a class of biomacromolecules with important biological functions (including photoprotection) and with the potential for certain bioengineering applications. We have used the difference of Self-Consistent Fields method to study the energy gap between the highest occupied molecular orbital and the lowest unoccupied molecular orbital, HL. We show that HL is similar in IQ and SQ, but approximately twice as large in HQ. This may have important implications for our understanding of the observed broadband optical absorption of the eumelanins. The possibility of using this difference in HL to molecularly engineer the electronic properties of eumelanins is discussed. We calculate the infrared and Raman spectra of the three redox forms from first principles. Each of the molecules have significantly different infrared and Raman signatures, and so these spectra could be used in situ to nondestructively identify the monomeric content of macromolecules. It is hoped that this may be a helpful analytical tool in determining the structure of eumelanin macromolecules and hence in helping to determine the structure-property-function relationships that control the behavior of the eumelanins.
-
a first principles density functional calculation of the electronic and vibrational structure of the key melanin monomers
arXiv: Biomolecules, 2004Co-Authors: Benjamin J Powell, Tunna Baruah, Noam Bernstein, K Brake, Ross H Mckenzie, Paul Meredith, Mark R PedersonAbstract:We report first principles density functional calculations for hydroquinone (HQ), indolequinone (IQ) and semiquinone (SQ). These molecules are believed to be the basic building blocks of the eumelanins, a class of bio-macromolecules with important biological functions (including photoprotection) and with potential for certain bioengineering applications. We have used the DeltaSCF (difference of Self Consistent Fields) method to study the energy gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO), Delta_HL. We show that Delta_HL is similar in IQ and SQ but approximately twice as large in HQ. This may have important implications for our understanding of the observed broad band optical absorption of the eumelanins. The possibility of using this difference in Delta_HL to molecularly engineer the electronic properties of eumelanins is discussed. We calculate the infrared and Raman spectra of the three redox forms from first principles. Each of the molecules have significantly different infrared and Raman signatures, and so these spectra could be used in situ to non-destructively identify the monomeric content of macromolecules. It is hoped that this may be a helpful analytical tool in determining the structure of eumelanin macromolecules and hence in helping to determine the structure-property-function relationships that control the behaviour of the eumelanins.