RESEARCH PRIORITIES



(I) TITANATE CRYSTALS
A wide range of research in titanates. In particular, at the moment we are 
involved in the following investigation:

(i) Free hole polarons in BaTiO3 cubic and tetragonal structure. Impurity 
     (donor and acceptor) doping in BaTiO3. Studies of Al- and Sc-bound hole 
     polarons: structure, lattice distortion, absorption energies. Studies of 
     La- and Nb-doped BaTiO3: impurity produced local energy levels in the 
     band-gap, lattice distortion, defect effect upon the absorption spectra. 
     (Henry Pinto and Edgar Javier Pati�o).

(ii) Radiation induced defects in SrTiO3: free hole polarons, impurity-bound
     polarons, F+ and F centres in cubic and tetragonal phases, their influence
     upon the structural and optical properties of SrTiO3. Effect of negatively
     charged electronic centres on the conductivity in the SrTiO3 tetragonal 
     lattice. (Arvids Stashans and Eduardo Alb�n).

(iii) La- and Nb-doping in SrTiO3: impurity effect on the electronic band 
     structure and superconductivity occurrence in this material. Studies 
     of the effect of the La concentration on the SrTiO3 structural and 
     electronic properties. (Paul S�nchez).

(iv) Studies of Zr-impurity doping in both crystallographical lattices of 
     PbTiO3: structural and electronic properties, dependence of crystal 
     properties of impurity concentration. (Alfredo S�nchez and Luis 
     Miguel Pr�cel).

(v) The surfaces of SrTiO3: electronic band structure and stability of 
     the following surfaces: (001), (110) and (111) in the cubic and
     tetragonal SrTiO3 phases. Oxygen vacancies, F+ and F centres on these 
     surfaces and their influence upon the structural and electronic 
     properties of the material. Molecular adsorption on the strontium 
     titanate (001) surface: geometry, chemical bonding. (Sheyla Serrano 
     and Ricardo Viteri).

(vi) Computational study of vacancy-defects (Vo and F centres) in cubic
     and tetragonal structures of PbTiO3 crystal: interpretation of structural,
     electronic and optical properties due to point defect presence in the
     material. Calculation of Vo and F migration in the crystalline lattice.
     (Sheyla Serrano).

(vii) Investigation of oxygen vacancies and F centres in the tetragonal
    BaTiO3 crystal and study of defects influence upon the properties of
    ferroelectricity. (Henry Pinto in collaboration with the Professor 
    Masahiko Morinaga, Nagoya University, Japan).

(viii) Study of H impurity in the bulk of BaTiO3 crystal: equilibrium
    positions, diffusion paths, influence upon the ferroelectricity.
    (Johnny Chimborazo).

(ix) Study of H impurity in the bulk of SrTiO3 crystal: equilibrium
    positions, diffusion paths, influence upon the ferroelectricity.
    (Luis Miguel Pr�cel and Rafael �ngel Barreto).

(x) Study of H impurity in the bulk of CaTiO3 crystal: equilibrium
    positions, diffusion paths, influence upon the ferroelectricity.
    (Milagros Castillo).

(xi) Oxygen-vacancy defects on the BaTiO3 (001) surface: structural,
    electronic and optical properties. (Carlos Duque).

(xii) Excitons in BaTiO3 and SrTiO3. (Arvids Stashans, Luis Miguel
    Pr�cel and Ricardo Viteri).

(xiii) Polarons and bipolarons in titanates (Arvids Stashans, Henry 
    Pinto and Carlos Duque).

(xiv) Al impurity in SrTiO3: structural and electronic properties. 
    (Juan Idrobo and Pa�l Pr�cel).

(xv) Nb and Al impurities in PZT materials: structural and 
    electronic properties, changes of dipolar moment. (Sheyla
    Serrano).



(II) DFT METHODS APPLIED TO CERAMIC MATERIALS
Studies of crystalline materials by means of the advanced Density-
Functional-Theory methods. (Henry Pinto and Edgar Javier Pati�o in 
collaboration with the Professor Risto Nieminen, Helsinki University 
of Technology, Finland).



(III) MOLECULAR CRYSTALS
Study of molecular crystals, mainly calixarenes: calculation of the
band structure and geometry of pure crystals as well as defects of
substitution. (Alfredo S�nchez, Ricardo Viteri, Luis Miguel Pr�cel, 
Wladimir Benalc�zar and Fanny Cuesta).



(IV) SUPERCONDUCTOR/FERROMAGNET INTERFACES
Phenomenological theory of superconductor/ferromagnet interfaces:
free energy, distribution of magnetic impurities, order parameters, 
domain walls. (Edgar Javier Pati�o in collaboration with scientists from
Helsinki University of Technology, Finland and Cambridge University,
England). 



(V) COSMOLOGY, A NEW FORMALISM OF THE 
    QUANTUM MECHANICS AND THE OTHER TOPICS 
    WITHIN THE THEORETICAL PHYSICS. 
    (Douglas Moya).




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