Clear["Global`*"]

<< DifferentialForms`

Izz1=0.001(*in kg*m^2*)

Izz2=0.001 (*in kg*m^2*)

m1 = 0.181 (*in kg*)

m2= 0.181 (*in kg*)

L1 = 0.250 (*in m*)

L2 =  0.250(*in m*)

xx = {Th1,Th2}

g={{Izz1+Izz2+(m2*(2*((L2*Cos[Th1+Th2])/2+L1*Cos[Th1])^2+2*((L2*Sin[Th1+Th2])/2+L1*Sin[Th1])^2))/2+(m1*((L1^2*Cos[Th1]^2)/2+(L1^2*Sin[Th1]^2)/2))/2,Izz2+(m2*(L2*Sin[Th1+Th2]*((L2*Sin[Th1+Th2])/2+L1*Sin[Th1])+L2*Cos[Th1+Th2]*((L2*Cos[Th1+Th2])/2+L1*Cos[Th1])))/2},{Izz2+(m2*(L2*Sin[Th1+Th2]*((L2*Sin[Th1+Th2])/2+L1*Sin[Th1])+L2*Cos[Th1+Th2]*((L2*Cos[Th1+Th2])/2+L1*Cos[Th1])))/2,Izz2+(m2*((L2^2*Cos[Th1+Th2]^2)/2+(L2^2*Sin[Th1+Th2]^2)/2))/2}} (*in kg*m^2*)

InverseMetric[g_]:=Simplify@Inverse@g

ChristoffelSymbol[g_,xx_]:=Block[{n,ig,res},n=2;
ig=InverseMetric[g];
res=Table[(1/2) Sum[ig[[λ,σ]]*(-D[g[[μ,ν]],xx[[σ]]]+D[g[[σ,ν]],xx[[μ]]]+D[g[[σ,μ]],xx[[ν]]]),{σ,1,n}],{λ,1,n},{μ,1,n},{ν,1,n}];
Simplify[res]]

GammaJeff = ChristoffelSymbol[g,xx]

RiemannTensor[g_,xx_]:=Block[{n,Chr,res},n=2;
Chr=ChristoffelSymbol[g,xx];
res=Table[D[Chr[[ρ,ν,σ]],xx[[μ]]]-D[Chr[[ρ,μ,σ]],xx[[ν]]]+Sum[Chr[[ρ,μ,λ]]*Chr[[λ,ν,σ]],{λ,1,n}]-Sum[Chr[[ρ,ν,λ]]*Chr[[λ,μ,σ]],{λ,1,n}],{ρ,1,n},{σ,1,n},{μ,1,n},{ν,1,n}];
Simplify[res]]

RiemannJeff = RiemannTensor[g,xx]

K = {1,0}.{RiemannJeff[[1]][[1]][[2]][[2]],RiemannJeff[[2]][[1]][[2]][[2]]}