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Physics and Astronomy

Quantum Systems and Nanomaterials Group

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G P Srivastava - Research interests

My research has concentrated on theoretical and computational studies of the physics of phonons and electrons in crystalline solids, surfaces and nano-structures. I have collaborated with various physicists, both experimentalists and theorists, of international reputation. This has led to over 390 publications, including two postgraduate books entitled The Physics of Phonons and Theoretical Modelling of Semiconductor Surfaces.

Current areas of research

Phonon Engineering of Nanocomposite Thermoelectric Materials

    Thermoelectricity (TE) is the process of generating either electricity from heat engines or heating devices from electricity. Examples of modern TE applications include portable refrigerators, beverage coolers, electronic component coolers, infrared sensing, etc. Possible future applications of TE devices include efficient conversion of waste heat (e.g. from waste and during powering of vehicles, etc) into usable energy, in improving the efficiency of photovoltaic cells, etc. It is being realised that material choice with reduced dimensionality is a prudent strategy for increasing the TE figure-of-merit (ZT) relative to bulk values. It is further believed that significant enhancement in ZT can be achieved by producing huge reduction in the lattice (phonon) thermal conductivity by fabricating 'nanocomposites' (in the form of superlattices, nanowired embedded matrices of larger dimensions, or nanodots embedded in matrices of larger dimensions). We are making a systematic theoretical investigations of this aspect by considering Si-based, Bi2Te3-based and PbTe-based nanocomposites.

Nanophononic Solids

    Our aim is to establish trends and criteria for the development of polarisation gaps as well as total band gaps in the phonon spectrum of 1D, 2D and 3D nanophononic semiconductor systems. These studies are made by employing a combination of the adiabatic bond charge model and the DFT-based first-principles pseudopotential method. We are developing a theory of phonon-defect and phonon-phonon interactions, and of phonon conductivity in such systems. These investigations are based on a combination of anharmonic elastic continuum theory, time-dependent perturbation theory, and a model relaxation time approach for the solution of the phonon Boltzmann equation. Project support: Leverhulme Trust.


    We are working on studies of the structural (equilibrium atomic positions), electronic states, phonon modes, phonon interactions, and thermal conductivity of semiconductor nanomaterials, such as wires and superlattices. Theoretical methods employed include the adiabatic bond charge model, the DFT-based first-principles pseudopotential method, a model relaxation time theory for thermal conductivity.

Graphene Systems

    We investigate equilibrium atomic geometry, stable structural shapes, electronic states, magnetic properties, phonon modes, and phonon lifetimes in graphene systes including monolayer graphene, bilayer graphene, multilayer graphene, graphite, and graphene nanoribbons. Theoretical methods include a combination of the DFT-based first-principles pseudopotential method, and an anharmonic elastic continuum theory. Collaborator: Dr. R. H. Miwa (University of Uberlandia, Brazil).

Solid Surfaces

    We make first-principles studies of adsorption and reactions on solids surfaces. (a) Atomic geometry, electronic states and phonon dispersion relations of clean semiconductor and metal surfaces. Collaborator: Professor H. M. Tutuncu (Sakarya University, Turkey). (b) Adsorption of atoms on III-V(001) surfaces. (c) Molecular adsorption on Si(111). Collaborators: Professor A. B. McLean (Queen's University, Canada) and Dr. R. H. Miwa (University of Uberlandia, Brazil). (d) Molecular adsorption on Si(100). Collaborator: Dr. M. Shimomura (Shizuoka University, Japan). (e) Dilute magnetic systems - atomic adsorption on III-V(110). Collaborator: Dr. M. Migliorato (Manchester University).

Bulk crystals

    First-principles studies of ground-state properties, electronic structure, lattice dynamics, electron-phonon interactions in the context of BCS theory of superconductivity. Collaborator: Professor H. M. Tutuncu (University of Sakarya, Turkey).

Previous Research


    Anharmonic phonon interactions; Theory of lattice thermal conductivity; Empirical pseudopotential method for electronic band structure of semiconductors; Pseudopotential theory of deep impurities in semiconductors.


    First-principles studies of atomic geometry, reconstrction and electronic structure of solids and semiconductor surfaces using the planewave pseudopotential method and the Density Function theory; Development of the pseudopotential-DFT and a simple GW theory and computer codes; Formulation and use of Broyden's Jacobian update method for accelerated self-consistent calculations.


    Development of theory and computer codes for lattice dynamical studies (i.e. phonon dispersion relations and phonon eigen displacements) of semiconductors and their surfaces using the adiabatic bond charge model and the first-principles pseudopotential method.


    First-principles studies of surface adsorption and reactions. First-principles studies of lattice dynamics using the pseudopotential method and the density functional scheme, to carry out full lattice dynamics of bulk, surfaces, and nanostructures. Application of our previously developed theory of anharmonic interactions and lattice thermal conductivity to nanostructures.
A brief description of my past research projects is available below.

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