Calculation of the Markovnikov transition state for H2O and HX (X = F, Cl, Br).
Validation of transition state using intrinsic reaction coordinate and vibrational frequency.
Quantitative agreement of transition state energy based on partition function.
Dipolar nature of transition state validated using Hirshfeld charge and Fukui function.
Explanation of Markovnikov regioselectivity for H2O based on dipolar transition state.