Exact Wave Function and Coherent States for a Time-Dependent Harmonic Oscillator

By using a trial wave function, the exact wave function for a harmonic oscillator with time? dependent mass, frequency, damping and driving is obtained. And then by defining a unitary operator, coherent states for the system of interest are found. These coherent states have most, but not all, of the properties the time independent oscillator. And all the results obtained can be reduced to the usual ones when both the mass and frequency are constants and the driving is absent.