Adiabatic and Diabatic Energy Data for the Ground and First Excited Singlet States of CH₃NH₂

This data set includes adiabatic energies from XMS-CASPT2/6-31++G(d,p) calculations and diabatic energies and couplings calculated using the dipole-quadrupole diabatization method for the ground and first excited singlet states of methylamine (CH₃NH₂) at 1825 geometry points. This data was used to construct an analytical diabatic potential energy matrix.