Hamiltonian matrix - Eigenvectors

In summary, the conversation discusses the construction and diagonalization of a non-diagonal Hamiltonian matrix using a complete set of orthogonal basis vectors. The resulting matrix represents the eigenvalues of the Hamiltonian, and another matrix composed of scalars represents the eigenvectors. The link between the scalar matrix and the basis vectors is that the columns of the scalar matrix are the coordinates of the eigenvectors on the basis vectors.
  • #1
Konte
90
1
Hello everybody,

From a complete set of orthogonal basis vector ##|i\rangle## ##\in## Hilbert space (##i## = ##1## to ##n##), I construct and obtain a nondiagonal Hamiltonian matrix
$$
\left( \begin{array}{cccccc}
\langle1|H|1\rangle & \langle1|H|2\rangle & . &. &.& \langle1|H|n\rangle \\
\langle2|H|1\rangle & . & . &. &.&. \\
. & . & . &. &.&. \\
. & . & . &. &.&. \\
. & . & . &. &.&. \\
. & . &. &. &.& \langle n|H|n\rangle \end{array} \right)
$$

After diagonalization, I obtain diagonal ##n\times n## matrix that represent the eigenvalues of the Hamiltonian, and another ##n\times n## matrix ##V## composed of scalars that represent the eigenvectors of the same Hamiltonian.

My question is, what is the link between the scalar matrix ##V## and the complete set of orthogonal basis vector ##|i\rangle## that I choose in the beginning ?

Thank you very much everybody.

Konte
 
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  • #2
As far as I know the ##\left | {i} \right \rangle ## are the base vectors for ##V##.

so ##V_{ni}## are the coefficients ##\left\langle e_n \middle | i \right \rangle## ; in other words:

Column n of ##V## are the coordinates of eigenvector ##e_n## on the basis ##\left | {i} \right \rangle ##
 
  • Like
Likes Konte and extranjero
  • #3
BvU said:
Column n of ##V## are the coordinates of eigenvector ##e_n## on the basis ##\left | {i} \right \rangle ##

Thanks.

Konte
 

1. What is a Hamiltonian matrix?

A Hamiltonian matrix is a square matrix used in mathematical physics to represent the total energy of a physical system. It is named after the Irish mathematician William Rowan Hamilton.

2. What is the significance of eigenvectors in a Hamiltonian matrix?

Eigenvectors in a Hamiltonian matrix represent the stationary states of a physical system, where the system's energy does not change over time. They are important in quantum mechanics and allow for the prediction of the system's future behavior.

3. How do you find the eigenvectors of a Hamiltonian matrix?

The eigenvectors of a Hamiltonian matrix can be found by solving the eigenvalue problem, which involves finding the values of lambda that satisfy the characteristic equation det(H - λI) = 0, where H is the Hamiltonian matrix and I is the identity matrix.

4. What is the relationship between eigenvectors and eigenvalues in a Hamiltonian matrix?

Eigenvectors and eigenvalues in a Hamiltonian matrix are closely related. Eigenvectors are the vectors that do not change direction when multiplied by the Hamiltonian matrix, and the corresponding eigenvalues represent the energy of the system in that state.

5. Can a Hamiltonian matrix have complex eigenvalues and eigenvectors?

Yes, a Hamiltonian matrix can have complex eigenvalues and eigenvectors. This is because in quantum mechanics, physical systems can exist in superposition, where they have both real and imaginary components. Complex eigenvectors and eigenvalues allow for the representation of these states in the Hamiltonian matrix.

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