The model β-sheet system described above was first optimized using a semi-empirical tight-binding model Hamiltonian as defined in the semi-empirical Geometry, Frequency, Noncovalent, eXtended tight-binding (GFN2-xTB). The GFN2-xTB Hamiltonian includes terms for multipole electrostatics and density-dependent dispersion, which can be important for inter-strand interactions. The GFN2-xTB method employs a minimal atomic orbital basis set, which helps mitigate the cost of calculations involving the relatively large model βsheet system. Vibrational normal modes were obtained using the GFN2-xTB method using the harmonic approximation.