Captain America's shield just needs to have a super power that works like magic because it does. 

An "Absorb and disperse" theory opens a big can of worms if it is used for more than just a quick line here and there.

If it just absorbs energy then it can't knock people down or bounce off of things. It just stops whatever collides with it if it is stationary and it just stops if it is moving. And if it absorbs a force then there is no reaction or rebound because the action that causes the reaction is removed from the system. So punching the shield would just make your fist stop with no scuffed knuckles or anything. Hitting someone with the shield wouldn't hurt them. The shield would just stop. Throwing the shield would have it stop and fall and not bounce when it encountered any object.

Maybe you could say that the shield diverts and disperses forces in some sort of active way that let's it decide what happens when a force hits it. Throw it at a bad guy's jaw? HIT. Bring it up in front of a tank gun? Disperse every thing over the lethal threshold and throw the wielder back with the remainder to show how powerful the blow was.

And you don't want to worry about the shield softening, or deforming at various points or changing its structure and composition or heating up, or vibrating to disperse the forces either. You don't want to worry about how it disperses or de-absorbs forces. You don't want to worry about how the incoming angles to the shield affect absorption/dispersion where maybe a force orthogonal to the curve of the shield (dead on) behaves differently that one that is almost parallel to the curve of the shield (parallel would be a miss).

It gets silly fast when you think about it. Firm rules are bad if they lead to derivatives that won't work the way the writer/artist wants them to.

Lately there is an urge to update the old explanations. where writers want to abandon radioactivity, mystery alloys, magnets, blood transfusions, ions, and transistors, and the go-to mysterious transformative enablers that people have heard of. 

I think the best pop-sci idea we have for a current (non WW2) explanation for the shields and  is that it is made of self-regulating nano-machines that constantly reconfigure themselves according to instructions from Captain America perhaps programmed through biofeedback that is good enough to guess what he wants by observing him. 

Even then we have jerks who will wonder why if it can change its structure to simulate various composites and materials it doesn't change shape enough to become a helmet or armor or if he can use it to pick any lock or otherwise radically change its shape. Or can he make it change color and luster? Can he make it turn invisible and use it for camouflage? Can he use it to display words and symbols? Can he make it like a mirror?

Details generally lead to trouble.