kerkerSolverProblemDevice.h

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// ---------------------------------------------------------------------
//
// Copyright (c) 2019-2020  The Regents of the University of Michigan and DFT-FE
// authors.
//
// This file is part of the DFT-FE code.
//
// The DFT-FE code is free software; you can use it, redistribute
// it, and/or modify it under the terms of the GNU Lesser General
// Public License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
// The full text of the license can be found in the file LICENSE at
// the top level of the DFT-FE distribution.
//
// ---------------------------------------------------------------------
//
 
 
 
#if defined(DFTFE_WITH_DEVICE)
 
#  ifndef kerkerSolverProblemDevice_H_
#    define kerkerSolverProblemDevice_H_
 
#    include <linearSolverProblemDevice.h>
#    include <triangulationManager.h>
#    include <constraintMatrixInfo.h>
#    include <MemoryStorage.h>
#    include <dftUtils.h>
#    include <FEBasisOperations.h>
 
 
namespace dftfe
{
  /**
   * @brief helmholtz solver problem class template. template parameter FEOrderElectro
   * is the finite element polynomial order for electrostatics
   *
   * @author Gourab Panigrahi
   */
  template <dftfe::uInt FEOrderElectro>
  class kerkerSolverProblemDevice : public linearSolverProblemDevice
  {
  public:
    /// Constructor
    kerkerSolverProblemDevice(const MPI_Comm &mpi_comm_parent,
                              const MPI_Comm &mpi_comm_domain);
 
 
    /**
     * @brief initialize the matrix-free data structures
     *
     * @param matrixFreeData structure to hold quadrature rule, constraints vector and appropriate dofHandler
     * @param constraintMatrix to hold constraints in the given problem
     * @param x vector to be initialized using matrix-free object
     *
     */
    void
    init(
      std::shared_ptr<
        dftfe::basis::
          FEBasisOperations<double, double, dftfe::utils::MemorySpace::DEVICE>>
                                        &basisOperationsPtr,
      dealii::AffineConstraints<double> &constraintMatrix,
      distributedCPUVec<double>         &x,
      double                             kerkerMixingParameter,
      const dftfe::uInt                  matrixFreeVectorComponent,
      const dftfe::uInt                  matrixFreeQuadratureComponent);
 
 
    /**
     * @brief reinitialize data structures .
     *
     * @param x vector to store initial guess and solution
     * @param gradResidualValues stores the gradient of difference of input electron-density and output electron-density
     * @param kerkerMixingParameter used in Kerker mixing scheme which usually represents Thomas Fermi wavevector (k_{TF}**2).
     *
     */
    void
    reinit(
      distributedCPUVec<double> &x,
      const dftfe::utils::MemoryStorage<double, dftfe::utils::MemorySpace::HOST>
        &quadPointValues);
 
 
    /**
     * @brief get the reference to x field
     *
     * @return reference to x field. Assumes x field data structure is already initialized
     */
    distributedDeviceVec<double> &
    getX();
 
 
    /**
     * @brief get the reference to Preconditioner
     *
     * @return reference to Preconditioner
     */
    distributedDeviceVec<double> &
    getPreconditioner();
 
 
    /**
     * @brief Compute A matrix multipled by x.
     *
     */
    void
    computeAX(distributedDeviceVec<double> &Ax,
              distributedDeviceVec<double> &x);
 
 
    void
    setX();
 
 
    /**
     * @brief Compute right hand side vector for the problem Ax = rhs.
     *
     * @param rhs vector for the right hand side values
     */
    void
    computeRhs(distributedCPUVec<double> &rhs);
 
 
    /**
     * @brief distribute x to the constrained nodes.
     *
     */
    void
    distributeX();
 
 
    /**
     * @brief Copies x from Device to Host
     *
     */
    void
    copyXfromDeviceToHost();
 
 
    /// function needed by dealii to mimic SparseMatrix for Jacobi
    /// preconditioning
    void
    subscribe(std::atomic<bool> *const validity,
              const std::string       &identifier = "") const {};
 
 
    /// function needed by dealii to mimic SparseMatrix for Jacobi
    /// preconditioning
    void
    unsubscribe(std::atomic<bool> *const validity,
                const std::string       &identifier = "") const {};
 
 
    /// function needed by dealii to mimic SparseMatrix
    bool
    operator!=(double val) const
    {
      return true;
    };
 
 
  private:
    /**
     * @brief Sets up the matrixfree shapefunction, gradient, jacobian and map for matrixfree computeAX
     *
     */
    void
    setupMatrixFree();
 
    /**
     * @brief Sets up the constraints matrix
     *
     */
    void
    setupConstraints();
 
    /**
     * @brief Compute the diagonal of A.
     *
     */
    void
    computeDiagonalA();
 
 
    /// storage for diagonal of the A matrix
    distributedCPUVec<double>    d_diagonalA;
    distributedDeviceVec<double> d_diagonalAdevice;
 
    /// pointer to the x vector being solved for
    distributedCPUVec<double> *d_xPtr;
 
    /// Device x vector being solved for
    distributedDeviceVec<double> d_xDevice;
 
    // number of cells local to each mpi task, number of degrees of freedom
    // locally owned and total degrees of freedom including ghost
    dftfe::Int d_nLocalCells, d_xLocalDof, d_xLen;
 
    // kerker mixing constant
    double d_gamma;
 
    // shape function value, gradient, jacobian and map for matrixfree
    dftfe::utils::MemoryStorage<double, dftfe::utils::MemorySpace::DEVICE>
      d_shapeFunction, d_jacobianFactor;
    dftfe::utils::MemoryStorage<dftfe::Int, dftfe::utils::MemorySpace::DEVICE>
      d_map;
 
    // Pointers to shape function value, gradient, jacobian and map for
    // matrixfree
    double     *d_shapeFunctionPtr;
    double     *d_jacobianFactorPtr;
    dftfe::Int *d_mapPtr;
 
    // constraints
    dftUtils::constraintMatrixInfo<dftfe::utils::MemorySpace::DEVICE>
      d_constraintsTotalPotentialInfo;
 
    /// matrix free index required to access the DofHandler and
    /// dealii::AffineConstraints<double> objects corresponding to the problem
    dftfe::uInt d_matrixFreeVectorComponent;
 
    /// matrix free quadrature index
    dftfe::uInt d_matrixFreeQuadratureComponent;
 
 
    /// pointer to electron density cell and grad residual data
    const dftfe::utils::MemoryStorage<double, dftfe::utils::MemorySpace::HOST>
                                            *d_residualQuadValuesPtr;
    const dealii::DoFHandler<3>             *d_dofHandlerPRefinedPtr;
    const dealii::AffineConstraints<double> *d_constraintMatrixPRefinedPtr;
    const dealii::MatrixFree<3, double>     *d_matrixFreeDataPRefinedPtr;
    std::shared_ptr<
      dftfe::basis::
        FEBasisOperations<double, double, dftfe::utils::MemorySpace::DEVICE>>
      d_basisOperationsPtr;
 
 
 
    const MPI_Comm             d_mpiCommParent;
    const MPI_Comm             mpi_communicator;
    const dftfe::uInt          n_mpi_processes;
    const dftfe::uInt          this_mpi_process;
    dealii::ConditionalOStream pcout;
  };
 
} // namespace dftfe
#  endif // kerkerSolverProblemDevice_H_
#endif