In quantum mechanics, the quantum virial theorem relates the time-independent expectation value of the kinetic energy (T) and the potential energy (V) of a system. Which of the following expressions correctly represents the quantum virial theorem?
a. ⟨T⟩ + ⟨V⟩ = 0
b. 2⟨T⟩ = -⟨V⟩
c. ⟨T⟩ = -2⟨V⟩
d. ⟨T⟩ + 2⟨V⟩ = 0