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Analytical Representation

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R Sayos – One of the best experts on this subject based on the ideXlab platform.

  • an Analytical Representation of the ground potential energy surface 2a of the h cl2 hcl cl and cl hcl hcl cl reactions based on ab initio calculations
    Journal of Chemical Physics, 1998
    Co-Authors: Miguel Gonzalez, J Hijazo, Juan J Novoa, R Sayos

    Abstract:

    In this work we have studied at an ab initio level the lowest 2A′ potential energy surface (PES) of the HCl2 system. This PES is involved in the H(2S)+Cl2(X 1Σg+)→HCl(X 1Σ+)+Cl(2P) and Cl(2P)+HCl(X 1Σ+)→HCl(X 1Σ+)+Cl(2P) gas phase elementary chemical reactions. The former reaction is an important chemical laser while the second one is the most frequently used prototype of heavy–light–heavy reaction. A large number of points on the 2A′ PES have been calculated at the PUMP2/6-311G(3d2 f,3p2d) ab initio level. The ab initio calculations show the existence of two angular transition states with negligible or very small barriers to collinearity. This and other properties of the PES are in agreement with previous studies. An Analytical expression based on a many-body expansion has been used to obtain a satisfactory fit of the 740 ab initio points calculated, with a root-mean-square deviation within the range of the estimated ab initio method error margin. This Analytical Representation of the 2A′ PES has been us…

  • An Analytical Representation of the ground potential energy surface (2A′) of the H+Cl2→HCl+Cl and Cl+HCl→HCl+Cl reactions, based on ab initio calculations
    Journal of Chemical Physics, 1998
    Co-Authors: Miguel Gonzalez, J Hijazo, Juan J Novoa, R Sayos

    Abstract:

    In this work we have studied at an ab initio level the lowest 2A′ potential energy surface (PES) of the HCl2 system. This PES is involved in the H(2S)+Cl2(X 1Σg+)→HCl(X 1Σ+)+Cl(2P) and Cl(2P)+HCl(X 1Σ+)→HCl(X 1Σ+)+Cl(2P) gas phase elementary chemical reactions. The former reaction is an important chemical laser while the second one is the most frequently used prototype of heavy–light–heavy reaction. A large number of points on the 2A′ PES have been calculated at the PUMP2/6-311G(3d2 f,3p2d) ab initio level. The ab initio calculations show the existence of two angular transition states with negligible or very small barriers to collinearity. This and other properties of the PES are in agreement with previous studies. An Analytical expression based on a many-body expansion has been used to obtain a satisfactory fit of the 740 ab initio points calculated, with a root-mean-square deviation within the range of the estimated ab initio method error margin. This Analytical Representation of the 2A′ PES has been us…

Elizabeth M Meiering – One of the best experts on this subject based on the ideXlab platform.

  • On the Analytical Representation of free energy profiles with a Morse/long-range model: Application to the water dimer
    Journal of Chemical Physics, 2013
    Co-Authors: Yalina Tritzant-martinez, Aron Broom, Tao Zeng, Elizabeth M Meiering

    Abstract:

    We investigate the Analytical Representation of potentials of mean force (pmf) using the Morse/long-range (MLR) potential approach. The MLR method had previously been used to represent potential energy surfaces, and we assess its validity for representing free-energies. The advantage of the approach is that the potential of mean force data only needs to be calculated in the short to medium range region of the reaction coordinate while the long range can be handled Analytically. This can result in significant savings in terms of computational effort since one does not need to cover the whole range of the reaction coordinate during simulations. The water dimer with rigid monomers whose interactions are described by the commonly used TIP4P model [W. Jorgensen and J. Madura, Mol. Phys. 56, 1381 (1985)]10.1080/00268978500103111 is used as a test case. We first calculate an “exact” pmf using direct Monte Carlo (MC) integration and term such a calculation as our gold standard (GS). Second, we compare this GS wit…

  • on the Analytical Representation of free energy profiles with a morse long range model application to the water dimer
    Journal of Chemical Physics, 2013
    Co-Authors: Yalina Tritzantmartinez, Tao Zeng, Aron Broom, Elizabeth M Meiering

    Abstract:

    We investigate the Analytical Representation of potentials of mean force (pmf) using the Morse/long-range (MLR) potential approach. The MLR method had previously been used to represent potential energy surfaces, and we assess its validity for representing free-energies. The advantage of the approach is that the potential of mean force data only needs to be calculated in the short to medium range region of the reaction coordinate while the long range can be handled Analytically. This can result in significant savings in terms of computational effort since one does not need to cover the whole range of the reaction coordinate during simulations. The water dimer with rigid monomers whose interactions are described by the commonly used TIP4P model [W. Jorgensen and J. Madura, Mol. Phys. 56, 1381 (1985)]10.1080/00268978500103111 is used as a test case. We first calculate an “exact” pmf using direct Monte Carlo (MC) integration and term such a calculation as our gold standard (GS). Second, we compare this GS wit…

Miguel Gonzalez – One of the best experts on this subject based on the ideXlab platform.

  • an Analytical Representation of the ground potential energy surface 2a of the h cl2 hcl cl and cl hcl hcl cl reactions based on ab initio calculations
    Journal of Chemical Physics, 1998
    Co-Authors: Miguel Gonzalez, J Hijazo, Juan J Novoa, R Sayos

    Abstract:

    In this work we have studied at an ab initio level the lowest 2A′ potential energy surface (PES) of the HCl2 system. This PES is involved in the H(2S)+Cl2(X 1Σg+)→HCl(X 1Σ+)+Cl(2P) and Cl(2P)+HCl(X 1Σ+)→HCl(X 1Σ+)+Cl(2P) gas phase elementary chemical reactions. The former reaction is an important chemical laser while the second one is the most frequently used prototype of heavy–light–heavy reaction. A large number of points on the 2A′ PES have been calculated at the PUMP2/6-311G(3d2 f,3p2d) ab initio level. The ab initio calculations show the existence of two angular transition states with negligible or very small barriers to collinearity. This and other properties of the PES are in agreement with previous studies. An Analytical expression based on a many-body expansion has been used to obtain a satisfactory fit of the 740 ab initio points calculated, with a root-mean-square deviation within the range of the estimated ab initio method error margin. This Analytical Representation of the 2A′ PES has been us…

  • An Analytical Representation of the ground potential energy surface (2A′) of the H+Cl2→HCl+Cl and Cl+HCl→HCl+Cl reactions, based on ab initio calculations
    Journal of Chemical Physics, 1998
    Co-Authors: Miguel Gonzalez, J Hijazo, Juan J Novoa, R Sayos

    Abstract:

    In this work we have studied at an ab initio level the lowest 2A′ potential energy surface (PES) of the HCl2 system. This PES is involved in the H(2S)+Cl2(X 1Σg+)→HCl(X 1Σ+)+Cl(2P) and Cl(2P)+HCl(X 1Σ+)→HCl(X 1Σ+)+Cl(2P) gas phase elementary chemical reactions. The former reaction is an important chemical laser while the second one is the most frequently used prototype of heavy–light–heavy reaction. A large number of points on the 2A′ PES have been calculated at the PUMP2/6-311G(3d2 f,3p2d) ab initio level. The ab initio calculations show the existence of two angular transition states with negligible or very small barriers to collinearity. This and other properties of the PES are in agreement with previous studies. An Analytical expression based on a many-body expansion has been used to obtain a satisfactory fit of the 740 ab initio points calculated, with a root-mean-square deviation within the range of the estimated ab initio method error margin. This Analytical Representation of the 2A′ PES has been us…