Note that the energy operator on the right-hand side of the equation takes an opposite sign convention as the one adopted in most textbooks of quantum mechanics. This is because COMSOL Multiphysics takes the engineering convention of exp(+iωt) for time-harmonic solutions, as opposed to the physics convention of exp(−iωt). The engineering convention is adopted for the Schrödinger Equation interface so that the sign convention is consistent within the COMSOL product family. Under this unusual sign convention, the momentum operator also acquires an opposite sign, since a plane wave is now exp(−ikx + iωt), not exp(+ikx − iωt) as in most textbooks.

For stationary studies, where the total energy E is a known quantity, enter a constant value or a global parameter for the Energy E (J) in the physics interface settings window (see section Energy).

For eigenvalue studies, where the eigenenergy E is unknown and to be solved for, enter a constant value for the Eigenvalue scale λscale (J) in the physics interface settings window (see section Eigenvalue Scale). The eigenenergy E is given by the product of the eigenvalue scale λscale and the eigenvalue λ (dimensionless). The default value for λscale is 1 eV, so that the eigenvalue λ takes on the numerical value of the eigenenergy E in units of eV.