Table 2: Thermodynamic parameters (kcal/mol)a for diphosphocytosine tautomers/rotamers at different levels in gas phase.

SpeciesB3LYPM06-2XMP2MP4(SDQ)b

PC13.707.015.784.666.8410.268.997.839.9013.2711.6111.387.19
PC20.000.620.500.460.000.720.580.500.400.420.420.380.46
PC30.470.000.000.000.400.000.000.000.000.000.000.000.00
PC424.7328.4326.9625.9925.9829.5228.1127.0527.4631.8030.4630.0124.82
PC524.5528.5326.8725.6326.0229.6828.2127.0128.1732.7526.7826.6825.51
PC622.2825.7324.3023.4623.5826.7525.4924.6724.7228.9026.9426.9122.23
PC722.1125.6424.1523.5423.1426.4925.1324.4424.8729.0926.940.0422.17
PC89.9716.6813.6512.6412.7619.5316.5015.4015.9123.1219.500.0313.96
PC912.0019.2115.9514.8214.1621.4618.2116.7317.8225.4821.6621.1115.68
PC105.378.907.566.448.8312.6511.219.9511.7815.2713.5613.249.63
PC110.920.480.500.460.9670.560.580.500.400.420.420.380.46
PC120.470.000.000.000.4000.000.000.000.000.000.000.000.00
PC1323.4727.0125.5724.7024.3127.8726.4825.1326.1330.6128.4127.8623.42
PC1425.1829.1427.5026.5625.9629.8128.2527.2627.6832.4930.120.0025.17
PC1520.5623.7122.3921.8621.2624.5023.1722.5522.9826.9224.900.0020.05
PC1621.7625.2323.7523.2322.4325.7624.3923.8123.9628.2126.0425.9921.24

Corrected for zero-point energy and thermal energy; buncorrected energy.