hh d ph e t ph f dh f sh theorem of boltzmannhafniumhalf cellhalf cell potentialhalf cell reactionhalf integer numberhalf lifehalf reactionhalf wave potentialhalf widthhaloform reactionhalogenhalogenated acidhalogenationhalogenshalohydrinhalonium ionhamiltonian functionhand torchhansa yellowhard acidhard basehard superconductorhard x rayhardenerhardeninghardnessharmonic motionharmonic oscillatorharmonic vibrationharmonic wavehartree equationhartree fock approximationhartree methodehartree theoryhartree unitshashishhauy lawheheadhead on collisionhead pressureheat capacityheat conductivityheat content