Hello, I am trying to plot the transmission coefficient vs energy for the double barrier potential, but I get an error. May I know what I have done wrong here?

V_0 = 0.2800; % Barrier strength in eV

hbar = 1.054571596e-34; % Reduced Planck constant

m = 5.465629128e-32; % 0.06*m_e

L = 1.00000e12; % Well width of the RTD

a = 1.00000e11; % Barrier width

x = 0.2801:0.0001:0.6000;

k = @(x) sqrt(2*m*x)/hbar;

etta = @(x) sqrt(2*m*(x-V_0))/hbar;

gamma = @(x) V_0/(x*sqrt(1-(V_0/x)));

nu = @(x) (2-(V_0/x))/(sqrt(1-(V_0/x)));

b = @(x) sin(k*L);

d = @(x) sin(2*k*L);

s = @(x) sin(etta*a);

u = @(x) sin(2*etta*a);

y = @(x) (1-gamma*b^2+nu*u^2-nu*gamma^2*d*u*s^2+4*gamma^4*b^2*s^4)^(-1);

plot(x,y), xlabel('E'), ylabel('T(E)')

Answer 1

[Alan Stevens]

See the following

V_0 = 0.2800; % Barrier strength in eV
hbar = 1.054571596e-34; % Reduced Planck constant
m = 5.465629128e-32; % 0.06*m_e
L = 1.00000e12; % Well width of the RTD
a = 1.00000e11; % Barrier width
x = 0.2801:0.0001:0.6000;
k = @(x) sqrt(2*m*x)/hbar;
etta = @(x) sqrt(2*m*(x-V_0))/hbar;
gamma = @(x) V_0./(x.*sqrt(1-(V_0./x)));       %%%%%% ./ and .* %%%%%%%%
nu = @(x) (2-(V_0./x))./(sqrt(1-(V_0./x)));    %%%%%% ./ and .* %%%%%%%%
b = @(x) sin(k(x)*L);                          % k is a function of x  %
d = @(x) sin(2*k(x)*L);                        % k is a function of x  %
s = @(x) sin(etta(x)*a);                       % etta is a function of x %
u = @(x) sin(2*etta(x)*a);                     % etta is a function of x %
y = @(x) (1-gamma(x).*b(x).^2+nu(x).*u(x).^2-... % gamma, b,nu, u etc are
    nu(x).*gamma(x).^2.*d(x).*u(x).*s(x).^2+...  % all functions of x
    4*gamma(x).^4.*b(x).^2.*s(x).^4).^(-1);      % Also note ./ and .*
plot(x,y(x)), xlabel('E'), ylabel('T(E)')      % y is a function of x

[Craig Egan Allistair Tan]

I have no issues getting the plots of k(x), etta(x), gamma(x), and nu(x) vs x, but if I try to plot y(x) vs x or even b(x) vs x, I get an error, and this is the error message that will pop up. How do I fix this? Thanks for the help, by the way.

[Alan Stevens]

I guess doublebarrier_transmission is the name of your program, but the listing above plots y(x) vs x ok.