Stress tensor calculations

define stress tensor

TstressTensor[i_,j_]:= (1/(4 π))(ϵ (Subscript[eField, [[i]]]) (Subscript[eField, [[j]]])-(1/2)KroneckerDelta[i,j]ϵ eField.eField+ μ (Subscript[bField, [[i]]]) (Subscript[bField, [[j]]])-(1/2)KroneckerDelta[i,j]μ bField.bField);

eField={E1,E2,E3};
bField={B1,B2,B3};
TstressMatrix=Table[TstressTensor[i,j],{i,1,3},{j,1,3}];
TstressMatrix=TstressMatrix /.{(E1^2)+(E2^2)+(E3^2)->(Etot^2),(B1^2)+(B2^2)+(B3^2)->(Btot^2)};
MatrixForm[TstressMatrix]

eField={0,0,E3};
bField=0{B1,B2,B3};
TstressMatrix=Table[TstressTensor[i,j],{i,1,3},{j,1,3}];
TstressMatrix=TstressMatrix /.{(E1^2)+(E2^2)+(E3^2)->(Etot^2),(B1^2)+(B2^2)+(B3^2)->(Btot^2)};
MatrixForm[TstressMatrix]

eField=0{E1,E2,E3};
bField={B1,B2,0};
TstressMatrix=Table[TstressTensor[i,j],{i,1,3},{j,1,3}];
TstressMatrix=TstressMatrix /.{(E1^2)+(E2^2)+(E3^2)->(Etot^2),(B1^2)+(B2^2)+(B3^2)->(Btot^2)};
MatrixForm[TstressMatrix]

define poynting vector

SpoyntingVector:=(c/(4 π))(1/μ)Cross[eField,bField];

MatrixForm[SpoyntingVector]