Glad to hear you figured out your problem with Spice. I hate little "gotcha's" like that. You can chase 'em for hours.About making a virtual circuit that models mechanical resonance, the idea is to find parallel L,C and R that acts as the mechanical resonator does. R will be set by Zmax, so that one is easy. Then, the values of C and L will be the same at resonance, and since Q is the ratio of reactive impedance to resistive impedance, you will find a the value of inductor and capacitor with reactances equal to Zmax / Qms at Fr.