I have been trying to create this Hamiltonian matrix, and I believe the complex exponential elements are giving me trouble. However, I don't know how to fix it.
This is what I have written so far:
t = 2.7
a = 1
z = -t * np.exp(-j*k*a)
y = -t * np.exp(j*k*a)
H = np.matrix(([0, -t,0,-t,0,0,0,0,0,0,0,0,0,0],
[- t, 0,- t ,0,0,0,0,0,0,0,0,0,0,0]
[0, - t ,0,y,0,-t,0,0,0,0,0,0,0,0]
[-t, 0,z,0,-t,0,0,0,0,0,0,0,0,0]
[0, 0,0,- t ,0,- t ,0,-t,0,0,0,0,0,0]
[0, 0,-t,0,0,-t,0,-t,0,0,0,0,0,0]
[0, 0,0,0,0,- t ,0,y,0,-t,0,0,0,0]
[0, 0,0,0,-t,0,z,0,- t,0,0,0,0,0]
[0, 0,0,0,0,0,0,- t,0,- t,0,-t,0,0]
[0, 0,0,0,0,0,-t,0,- t,0,- t,0,0,0]
[0, 0,0,0,0,0,0,0,0,- t,0,y,0,-t]
[0, 0,0,0,0,0,0,0,-t,0,z,0,- t,0]
[0, 0,0,0,0,0,0,0,0,0,0,- t ,0,- t]
[0, 0,0,0,0,0,0,0,0,0,-t,0,- t ,0]),dtype = np.complex)`
When I try to run the cell, this error message appears
TypeError: list indices must be integers or slices, not tuple
The matrix needs to be a 14x14 one so that I can code and obtain the eigenvalues and eigenvectors.
In the past I have used np.array to build matrices, and it has worked fine. However, for this one it didn't. As can be seen, I have also tried using np.matrix.
Try using
np.array([[val1, val2], [val3, val4]])
instead of
np.array(([val1, val2] [val3, val4])) ...
You got the error because of the commas in between the rows. Don't forget them otherwise Python thinks you are trying to do list indexing:
I.e.
[1,2,3][0]
Output: 1
Whereas
[1,2,3], [0]
Output:
([1,2,3], [0])