Module solver 

Generalized eigenproblem solver for EHT: HC = SCE.

Uses Löwdin orthogonalization:

1. Diagonalize S → eigenvalues λ, eigenvectors U
2. Build S^{-1/2} = U diag(1/√λ) U^T
3. Transform H’ = S^{-1/2} H S^{-1/2}
4. Diagonalize H’ → eigenvalues E, eigenvectors C’
5. Back-transform C = S^{-1/2} C’

Structs

EhtResult

Result of an EHT calculation.

Functions

solve_eht

Run the full EHT calculation pipeline.

solve_generalized_eigenproblem

Solve the generalized eigenproblem HC = SCE using Löwdin orthogonalization.