Constructing Potential Energy Surfaces for Polyatomic Systems: Recent Progress and New Problems

Table 1

CH₅ saddle point properties.^a

	Fitting (ZBB3)^b	Analytical (CBE)^c	Interpolated (ZFWCZ)^d
Barrier height	14.78	15.01	15.03
Geometry
R(C–H′)	1.409	1.390	1.399
R(H′–HB)	0.901	0.973	0.895
<H-C-H′	102.8	106.8	103.1
<C–H′–HB	180.0	180.0	180.0
Vibrational frequencies
	3289	3173	3223
	3289	3173	3223
	3104	3036	3073
	1726	1833	1784
	1434	1443	1442
	1434	1443	1442
	1078	1173	1115
	1078	1173	1115
	1062	1085	1062
	440	542	522
	440	542	522
	1320i	1488i	1467i

aEnergy in kcal mol⁻¹, geometry in Å and degrees, and vibrational frequency in cm⁻¹; b[55]; c[41]; d[18].