CCSD(T)/Def2-TZVPP/SCRF=dichloromethane  

HCCH                         HCC• + H•                        CC + H•

-77.1921235  =   (-76.471186  +  -0.4998248)  = (-75.7855463  +  -0.4998248)

-77.1921235  = -76.9710108,  -76.471186  =  -76.2853711
      
ΔE  138.7;                   ΔE     116.6   
      
ΔΔE = 22.1 kcal/mol