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Browsing by Author "Coelho, Daniela V."

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  • A full dimensional potential for H2O2 (X(1)A) covering all dissociation channels
    Publication . Coelho, Daniela V.; Brandão, J.
    This work presents a new full dimensional potential energy surface for the ground singlet state of hydrogen peroxide, H2O2. This potential is based on a 3 x 3 matrix to accurately reproduce all the different dissociation channels in accordance with the Wigner-Witmer rules, namely, O(D-1) + H2O(X(1)A(1)), OH(X-2 Pi) + OH(X-2 Pi), O-2(a(1)Delta(g)) + H-2(X-1 Sigma(+)(g)) e H(S-2) + HO2(X(2)A ''). It has been obtained by fitting more than 38 thousand ab initio energies computed using the aug-cc-pVTZ and aug-cc-pVQZ basis sets and extrapolated to the basis set limit. The functional form used to represent the four-body short-range interactions is based on a sum of polynomial functions of the fourth degree multiplied by a range factor, both built with intrinsic permutation symmetry and centred at specific reference geometries, to which the ab initio points computed are assigned based on a k-means algorithm. It also accounts for the electrostatic dipole-dipole interaction between two OH((2)Pi) fragments.
    2017-01Journal article Restricted access Show more
  • Internal energy and temperature of a carbon nanotube
    Publication . Coelho, Daniela V.; Brandão, João; Mogo, César
    Modelling the hydrogen combustion reaction confined in carbon nanotubes (CNTs) implies the effective control of the initial conditions of position and velocities of the gas and of the nanocontainer, so as to reproduce the pressure and temperature of the system. In this work, the initial conditions of the gas particles were randomly generated according to the Maxwell-Boltzmann distributions at a given temperature. As for the CNT structure, we follow a procedure which relates the internal energy of the CNT to its temperature, which allowed us to define the kinetic energy to distribute in order to obtain a CNT at the same temperature as the reactive mixture. Results indicate that we can locate the carbon atoms at their equilibrium geometries and use 3Nk(B)T for their average kinetic energy.
    2022-01Journal article Restricted access Show more