public override bool Run()
{
if (!initialise_from_restart)
{
// calculate the bare potential
Console.WriteLine("Calculating bare potential");
chem_pot = Physics_Base.q_e * pois_solv.Get_Potential(0.0 * carrier_charge_density.Spin_Summed_Data);
Console.WriteLine("Saving bare potential");
(Input_Band_Structure.Get_BandStructure_Grid(layers, dx_dens, dy_dens, dz_dens, nx_dens, ny_dens, nz_dens, xmin_dens, ymin_dens, zmin_dens) - chem_pot).Save_Data("bare_pot.dat");
Console.WriteLine("Bare potential saved");
//if the initial carrier density was not zero, recalculate the chemical potential
if (carrier_charge_density.Spin_Summed_Data.Max() != 0.0 || carrier_charge_density.Spin_Summed_Data.Min() != 0.0)
{
chem_pot = Physics_Base.q_e * pois_solv.Get_Potential(carrier_charge_density.Spin_Summed_Data);
}
}
// get the dopent density from the Poisson equation
dopent_charge_density.Spin_Up = -0.5 * (chem_pot.Laplacian / Physics_Base.q_e + carrier_charge_density.Spin_Summed_Data);
dopent_charge_density.Spin_Down = -0.5 * (chem_pot.Laplacian / Physics_Base.q_e + carrier_charge_density.Spin_Summed_Data);
// ThreeD_ThomasFermiSolver dens_solv = new ThreeD_ThomasFermiSolver(this);
//ThreeD_EffectiveBandSolver dft_solv = new ThreeD_EffectiveBandSolver(this);
// TwoplusOneD_ThomasFermiSolver dft_solv = new TwoplusOneD_ThomasFermiSolver(this);
bool converged = false;
// start without dft if carrier density is empty
if (no_dft || carrier_charge_density.Spin_Summed_Data.Min() == 0.0)
{
dens_solv.DFT_Mixing_Parameter = 0.0;
}
else
{
dens_solv.DFT_Mixing_Parameter = dft_mixing_parameter;
}
// do preliminary run to correct for initial discretised form of rho_prime
if (initial_run)
{
converged = Run_Iteration_Routine(dens_solv, pois_solv, tol, initial_run_steps);
// and calculate the potential given the density from this initial run
pois_solv.Initiate_Poisson_Solver(device_dimensions, boundary_conditions);
chem_pot = Physics_Base.q_e * pois_solv.Get_Potential(carrier_charge_density.Spin_Summed_Data);
}
if (!converged || !initial_run)
//if(true)
{
int count = 0;
while (pot_init > tol_anneal && count < 20)
{
if (count != 0)
{
pois_solv.Initiate_Poisson_Solver(device_dimensions, boundary_conditions);
chem_pot = Physics_Base.q_e * pois_solv.Get_Potential(carrier_charge_density.Spin_Summed_Data);
}
// run the iteration routine!
converged = Run_Iteration_Routine(dens_solv, pois_solv, tol, max_iterations);
count++;
}
}
// save surface charge
StreamWriter sw = new StreamWriter("surface_charge.dat"); sw.WriteLine(boundary_conditions["surface"].ToString()); sw.Close();
// save eigen-energies
/*DoubleVector energies = dft_solv.Get_EnergyLevels(layers, chem_pot);
* StreamWriter sw_e = new StreamWriter("energies.dat");
* for (int i = 0; i < energies.Length; i++)
* sw_e.WriteLine(energies[i]);
* sw_e.Close();*/
dens_solv.Output(carrier_charge_density, "carrier_density.dat");
dens_solv.Output(carrier_charge_density - dens_solv.Get_ChargeDensity(layers, carrier_charge_density, dopent_charge_density, chem_pot), "density_error.dat");
(Input_Band_Structure.Get_BandStructure_Grid(layers, dx_dens, dy_dens, dz_dens, nx_dens, ny_dens, nz_dens, xmin_dens, ymin_dens, zmin_dens) - chem_pot).Save_Data("potential.dat");
Band_Data pot_exc = dens_solv.DFT_diff(carrier_charge_density) + dens_solv.Get_XC_Potential(carrier_charge_density);
pot_exc.Save_Data("xc_pot.dat");
(Input_Band_Structure.Get_BandStructure_Grid(layers, dx_dens, dy_dens, dz_dens, nx_dens, ny_dens, nz_dens, xmin_dens, ymin_dens, zmin_dens) - chem_pot + pot_exc).Save_Data("pot_KS.dat");
// Band_Data ks_ke = dft_solv.Get_KS_KE(layers, chem_pot);
// ks_ke.Save_Data("ks_ke.dat");
// clean up intermediate data files
File.Delete("phi.dat");
File.Delete("new_phi.dat");
File.Delete("x.dat");
File.Delete("y.dat");
File.Delete("gphi.dat");
File.Delete("car_dens.dat");
File.Delete("rho_prime.dat");
File.Delete("xc_pot.dat");
File.Delete("xc_pot_calc.dat");
File.Delete("pot.dat");
File.Delete("carrier_density.dat");
File.Delete("charge_density.dat");
File.Delete("potential.dat");
File.Delete("lap.dat");
Close(dens_solv.Unit_Charge, converged, max_iterations);
return(converged);
}
protected override bool Run_Iteration_Routine(IDensity_Solve dens_solv, IPoisson_Solve pois_solv, double tol, int max_iterations)
{
// calculate initial potential with the given charge distribution
Console.WriteLine("Calculating initial potential grid");
pois_solv.Initiate_Poisson_Solver(device_dimensions, boundary_conditions);
if (chem_pot == null)
chem_pot = Physics_Base.q_e * pois_solv.Get_Potential(carrier_charge_density.Spin_Summed_Data + dopent_charge_density.Spin_Summed_Data);
Console.WriteLine("Initial grid complete");
// dens_solv.Set_DFT_Potential(carrier_charge_density);
// dens_solv.Get_ChargeDensity(layers, ref carrier_charge_density, ref dopent_charge_density, chem_pot);
// dens_solv.Set_DFT_Potential(carrier_charge_density);
dens_solv.Reset_DFT_Potential();
dens_solv.Update_DFT_Potential(carrier_charge_density);
int count = 0;
t = 1.0;
bool converged = false;
while (!converged)
{
Band_Data dens_old = carrier_charge_density.Spin_Summed_Data + dopent_charge_density.Spin_Summed_Data;
// Get charge rho(phi)
dens_solv.Get_ChargeDensity(layers, ref carrier_charge_density, ref dopent_charge_density, chem_pot);
// Generate charge-dependent part of the Jacobian, g'(phi) = -d(eps * d( )) - rho'(phi)
SpinResolved_Data rho_prime = dens_solv.Get_ChargeDensity_Deriv(layers, carrier_charge_density_deriv, dopent_charge_density_deriv, chem_pot);
// Solve stepping equation to find raw Newton iteration step, g'(phi) x = - g(phi)
// Calculate Laplacian operating on the given band energy, d(eps * d(phi))
gphi = -1.0 * chem_pot.Laplacian / Physics_Base.q_e - carrier_charge_density.Spin_Summed_Data - dopent_charge_density.Spin_Summed_Data;
gphi[0] = 0.0; gphi[gphi.Length - 1] = 0.0;
x = pois_solv.Calculate_Newton_Step(rho_prime, gphi);
// Calculate optimal damping parameter, t
t = t_damp * Calculate_optimal_t(t / t_damp, (chem_pot / Physics_Base.q_e), x, carrier_charge_density, dopent_charge_density, pois_solv, dens_solv, t_min);
// Check convergence
Band_Data dens_spin_summed = carrier_charge_density.Spin_Summed_Data + dopent_charge_density.Spin_Summed_Data;
Band_Data dens_diff = dens_spin_summed - dens_old;
double dens_abs_max = Math.Max(Math.Abs(dens_spin_summed.Max()), Math.Abs(dens_spin_summed.Min()));
for (int i = 0; i < dens_diff.Length; i++)
// only calculate density difference for densities more than 1% of the maximum value
if (Math.Abs(dens_spin_summed[i]) > 0.01 * dens_abs_max)
dens_diff[i] = Math.Abs(dens_diff[i] / dens_spin_summed[i]);
else
dens_diff[i] = 0.0;
// Update the DFT potential
dens_solv.Update_DFT_Potential(carrier_charge_density);
double[] diff = new double[Nz_Pot];
for (int j = 0; j < nz_pot; j++)
diff[j] = Math.Abs(gphi.vec[j]);
double convergence = diff.Sum();
if (Physics_Base.q_e * x.InfinityNorm() < tol)
converged = true;
// update band energy phi_new = phi_old + t * x
Console.WriteLine(Generate_Output_String(count, x, dens_diff));
chem_pot = chem_pot + t * Physics_Base.q_e * x;
count++;
base.Checkpoint();
// reset the potential if the added potential t * x is too small
if (converged || count > max_iterations)
{
Console.WriteLine("Maximum potential change at end of iteration was " + (t * Physics_Base.q_e * x.InfinityNorm()).ToString() + "meV");
break;
}
}
Console.WriteLine("Iteration complete");
return converged;
}
protected override bool Run_Iteration_Routine(IDensity_Solve dens_solv, IPoisson_Solve pois_solv, double tol, int max_iterations)
{
// calculate initial potential with the given charge distribution
Console.WriteLine("Calculating initial potential grid");
pois_solv.Initiate_Poisson_Solver(device_dimensions, boundary_conditions);
if (chem_pot == null)
{
chem_pot = Physics_Base.q_e * pois_solv.Get_Potential(carrier_charge_density.Spin_Summed_Data + dopent_charge_density.Spin_Summed_Data);
}
Console.WriteLine("Initial grid complete");
// dens_solv.Set_DFT_Potential(carrier_charge_density);
// dens_solv.Get_ChargeDensity(layers, ref carrier_charge_density, ref dopent_charge_density, chem_pot);
// dens_solv.Set_DFT_Potential(carrier_charge_density);
dens_solv.Reset_DFT_Potential();
dens_solv.Update_DFT_Potential(carrier_charge_density);
int count = 0;
t = 1.0;
bool converged = false;
while (!converged)
{
Band_Data dens_old = carrier_charge_density.Spin_Summed_Data + dopent_charge_density.Spin_Summed_Data;
// Get charge rho(phi)
dens_solv.Get_ChargeDensity(layers, ref carrier_charge_density, ref dopent_charge_density, chem_pot);
// Generate charge-dependent part of the Jacobian, g'(phi) = -d(eps * d( )) - rho'(phi)
SpinResolved_Data rho_prime = dens_solv.Get_ChargeDensity_Deriv(layers, carrier_charge_density_deriv, dopent_charge_density_deriv, chem_pot);
// Solve stepping equation to find raw Newton iteration step, g'(phi) x = - g(phi)
// Calculate Laplacian operating on the given band energy, d(eps * d(phi))
gphi = -1.0 * chem_pot.Laplacian / Physics_Base.q_e - carrier_charge_density.Spin_Summed_Data - dopent_charge_density.Spin_Summed_Data;
gphi[0] = 0.0; gphi[gphi.Length - 1] = 0.0;
x = pois_solv.Calculate_Newton_Step(rho_prime, gphi);
// Calculate optimal damping parameter, t
t = t_damp * Calculate_optimal_t(t / t_damp, (chem_pot / Physics_Base.q_e), x, carrier_charge_density, dopent_charge_density, pois_solv, dens_solv, t_min);
// Check convergence
Band_Data dens_spin_summed = carrier_charge_density.Spin_Summed_Data + dopent_charge_density.Spin_Summed_Data;
Band_Data dens_diff = dens_spin_summed - dens_old;
double dens_abs_max = Math.Max(Math.Abs(dens_spin_summed.Max()), Math.Abs(dens_spin_summed.Min()));
for (int i = 0; i < dens_diff.Length; i++)
{
// only calculate density difference for densities more than 1% of the maximum value
if (Math.Abs(dens_spin_summed[i]) > 0.01 * dens_abs_max)
{
dens_diff[i] = Math.Abs(dens_diff[i] / dens_spin_summed[i]);
}
else
{
dens_diff[i] = 0.0;
}
}
// Update the DFT potential
dens_solv.Update_DFT_Potential(carrier_charge_density);
double[] diff = new double[Nz_Pot];
for (int j = 0; j < nz_pot; j++)
{
diff[j] = Math.Abs(gphi.vec[j]);
}
double convergence = diff.Sum();
if (Physics_Base.q_e * x.InfinityNorm() < tol)
{
converged = true;
}
// update band energy phi_new = phi_old + t * x
Console.WriteLine(Generate_Output_String(count, x, dens_diff));
chem_pot = chem_pot + t * Physics_Base.q_e * x;
count++;
base.Checkpoint();
// reset the potential if the added potential t * x is too small
if (converged || count > max_iterations)
{
Console.WriteLine("Maximum potential change at end of iteration was " + (t * Physics_Base.q_e * x.InfinityNorm()).ToString() + "meV");
break;
}
}
Console.WriteLine("Iteration complete");
return(converged);
}
