Table 1. Optimized Molecular Geometries for the FPMD Simulation (Length and Angle Units are in Å and Degree, Respectively).

molecule	geometry	optimized	experimental	error (%)
cyclobutadiene	rCC1	1.347	1.38072	–2.4
	rCC2	1.571	1.56072	0.7
	rCH	1.094
	α1	134.62
	α2	135.38
ethylene	rCC	1.343	1.33573	0.6
	rCH	1.098	1.09073	0.7
	αHCC	121.51	121.773	–0.2
methane	rCH	1.102	1.08674	1.5
	αHCH	109.47
water	rOH	0.971	0.95975	1.3
	αHOH	104.79	103.975	0.9