Orbitals = {"1s","2s"}
Indices, NF = CreateAtomicIndicesDict(Orbitals)
e1s = 1
e2s = 2
F0ss = 0.5
O = NewOperator("Number", NF, Indices["1s"], Indices["1s"],{e1s, e1s})
    + NewOperator("Number", NF, Indices["2s"], Indices["2s"],{e2s, e2s})
    + NewOperator("U", NF, Indices["1s_Up"], Indices["1s_Dn"],{F0ss})
    + NewOperator("U", NF, Indices["2s_Up"], Indices["2s_Dn"],{F0ss})  
O.Name = "Operator"
print(O)

print("Set Operator trace average to 0")
OperatorSetOnsiteEnergy(O)
print(O)

print("Set Operator trace average to 2")
OperatorSetOnsiteEnergy(O,2)
print(O)

print("Set trace average of 1s orbitals to -1, and trace average of 2s orbitals to 15")
OperatorSetOnsiteEnergy(O,-1,Indices["1s"])
OperatorSetOnsiteEnergy(O,15,Indices["2s"])
print(O)