I need help with my code

Here is the error I am getting:

Error using calculate_fluctuation_dissipation_factor

Too many input arguments.

Error in Fluctuational_electrodynamics_main (line 36)

G = calculate_fluctuation_dissipation_factor(layer_properties(i), layer_properties(i+1), gap);

Below is the code I used:

% Define the material properties and temperatures of the layers
layer_properties = [...
    struct('conductivity', 0, 'n_fun', @(omega) refractive_index_real(omega, 1), 'k_fun', @(omega) refractive_index_imag(omega, 1), 'T', 400); % Layer 1 (top)
    struct('conductivity', 0, 'n_fun', @(omega) refractive_index_real(omega, 2), 'k_fun', @(omega) refractive_index_imag(omega, 2), 'T', 300); % Layer 2
    % Define the thicknesses of the layers
    layer_thicknesses = [500e-9, 1e-6]; % m
    
    % Define the distance between the multilayer stack and the reference surface
    d = 100e-9; % m rep. the distance between upper (emitter) and lower (PV cell)
    omega = linspace(0, 1e15, 1000); % rad/s
    % Calculate the heat transfer rate
    q = 0;
    for i = 1:length(layer_properties)-1
    % Calculate the fluctuation-dissipation factor
    gap = d + sum(layer_thicknesses(1:i));
    G = calculate_fluctuation_dissipation_factor(layer_properties(i), layer_properties(i+1), gap);
    
    % Calculate the temperature difference
    dT = layer_properties(i).T - layer_properties(i+1).T;
    
    % Add the contribution of this pair of layers to the total heat transfer rate
    q = q + G * dT^2;
    end

The first function defination

    function G = calculate_fluctuation_dissipation_factor(layer_properties, gap)
    % Define constants
    c = 3e8; % m/s
    h = 6.62607004e-34; % J.s
    k = 1.38064852e-23; % J/K
    
    % Define the frequency range
    omega = linspace(0, 1e15, 1000); % rad/s
    
    % Calculate the Bose-Einstein distribution function
    n1 = 1./(exp(h*omega./(k*layer_properties(1).T)) - 1);
    n2 = 1./(exp(h*omega./(k*layer_properties(2).T)) - 1);
    
    % Calculate the material's dielectric function
    epsilon1 = layer_properties(1).refractive_index^2 - 0*omega*1i./(c*omega); % Non-conductive material, set conductivity to zero
    epsilon2 = layer_properties(2).refractive_index^2 - 0*omega*1i./(c*omega); % Non-conductive material, set conductivity to zero
    
    % Calculate the reflection and transmission coefficients
    [R, T] = fresnel(epsilon1, epsilon2, omega, gap);
    
    % Calculate the fluctuation-dissipation factor
    G = (pi/6) * c * trapz((n1 + 1).*(n2 + 1).*(R + T).*epsilon1.*omega.^2);
    
    % Scale the fluctuation-dissipation factor by the distance between the surfaces
    G = G./gap^2;
    
    end

The second function

    function n = refractive_index_real(omega, layer_index)
    % Calculate the real part of the refractive index for a given layer as a
    % function of the angular frequency
    
    % Define the parameters for the refractive index function using lorentz
    % oscillator model
    parameters = [...
        % Layer 1
        struct('omega_0', 1e15, 'gamma', 8.9e11, 'n_inf', 6.7); % Layer 1 sic
        % Layer 2
        struct('omega_0', 1e15, 'gamma', 8.9e11, 'n_inf', 8.9e11); % Layer 2 sic
        % Layer 3
        %struct('omega_0', 3e15, 'gamma', 1e15, 'n_inf', 1.7); % Layer 3
        ];
    
    % Extract the parameters for the given layer
    omega_0 = parameters(layer_index).omega_0;
    gamma = parameters(layer_index).gamma;
    n_inf = parameters(layer_index).n_inf;
    
    % Calculate the real part of the refractive index
    n = n_inf - omega_0^2./(omega.^2 + 1i*gamma*omega);

Answer 1

[Voss]

The function calculate_fluctuation_dissipation_factor takes two inputs, the first of which is a vector with (at least) two elements, as can be seen from the function definition:

function G = calculate_fluctuation_dissipation_factor(layer_properties, gap)
% ...
n1 = 1./(exp(h*omega./(k*layer_properties(1).T)) - 1);
n2 = 1./(exp(h*omega./(k*layer_properties(2).T)) - 1);
% ...
end

But you are calling the function with three inputs:

G = calculate_fluctuation_dissipation_factor(layer_properties(i), layer_properties(i+1), gap);

Instead, layer_properties(i) and layer_properties(i+1) should be together in a single vector, as the first input:

G = calculate_fluctuation_dissipation_factor(layer_properties([i i+1]), gap);

[Ambali Odebowale]

Here is the error I am getting now:

Reference to non-existent field 'refractive_index_real'.

Error in calculate_fluctuation_dissipation_factor (line 16)

epsilon1 = layer_properties(1).refractive_index_real^2 - 0*omega*1i./(c*omega); % Non-conductive material, set conductivity to zero

Error in Fluctuational_electrodynamics_main (line 37)

G = calculate_fluctuation_dissipation_factor(layer_properties([i i+1]), gap);

[Voss]

That error happens because layer_properties does not have a field called 'refractive_index_real'. (refractive_index_real is a function you have defined; it's not a field of layer_properties.)

layer_properties = [...
    struct('conductivity', 0, 'n_fun', @(omega) refractive_index_real(omega, 1), 'k_fun', @(omega) refractive_index_imag(omega, 1), 'T', 400); % Layer 1 (top)
    struct('conductivity', 0, 'n_fun', @(omega) refractive_index_real(omega, 2), 'k_fun', @(omega) refractive_index_imag(omega, 2), 'T', 300); % Layer 2
    ] % <- this seems to be missing in your code, by the way

layer_properties = 2×1 struct array with fields:
    conductivity
    n_fun
    k_fun
    T

As you can see, the fields of layer_properties are 'conductivity', 'n_fun', 'k_fun', and 'T'.

The code in your question refers to the field 'refractive_index' of layer_properties, which also doesn't exist.

% Calculate the material's dielectric function
epsilon1 = layer_properties(1).refractive_index^2 - 0*omega*1i./(c*omega); % Non-conductive material, set conductivity to zero
epsilon2 = layer_properties(2).refractive_index^2 - 0*omega*1i./(c*omega); % Non-conductive material, set conductivity to zero

Perhaps you mean:

epsilon1 = layer_properties(1).n_fun(omega).^2 - 0*omega*1i./(c*omega); % Non-conductive material, set conductivity to zero
epsilon2 = layer_properties(2).n_fun(omega).^2 - 0*omega*1i./(c*omega); % Non-conductive material, set conductivity to zero

?

[Ambali Odebowale]

Hmm! I get what you said. I will check it out now.

Answer 2

[Byron Angulo]

G = calculate_fluctuation_dissipation_factor(layer_properties([i i+1]), gap);