Density matrices in spin-orbital and coordinate representations

3 DENSITY MATRICES IN SPIN-ORBITAL AND COORDINATE REPRESENTATIONS 

The density matrices we have discussed so far in this section have all been given in the spin-orbital representation. We shall now see how these matrices are represented in the coordinate 

We recall that, in the coordinate representation of first quantization, we may write the expectation value of any one-electron operator in the following form 

The density matrix in the spin-orbital representation was introduced in second quantization for the evaluation of one-electron expectation values in the following form 

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