RDM2 - Maple Help
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QuantumChemistry

 RDM2
 compute the spin-free 2-electron reduced density matrix (2-RDM)

 Calling Sequence RDM2(molecule, method, options)

Parameters

 molecule - list of lists; each list has 4 elements, the string of an atom's symbol and atom's x, y, and z coordinates method - (optional)  method = name/procedure where name is one of options - (optional) equation(s) of the form option = value where option is any valid option of the chosen method

Description

 • The RDM2(molecule) command computes the spin-free 2-electron reduced density matrix (2-RDM).
 • The output is a 4-index Array with dimensions  r x r x r x r, where r is the number of the orbitals.
 • The element A[i,k,j,l] of the output Array correponds to the element of the 2-RDM D2[i,j,k,l].
 • The default method is the 'MP2' method.
 • The result depends upon the chosen molecule, method, and basis set among other options such as charge, spin, and symmetry.
 • Because the methods employ Maple cache tables, the procedure only computes the 2-RDM if it has not been previously computed by calling the method directly or indirectly through another property.

Examples

 > $\mathrm{with}\left(\mathrm{QuantumChemistry}\right):$

Consider the molecule hydrogen fluoride

 >
 ${\mathrm{molecule}}{≔}\left[\left[{"H"}{,}{0}{,}{0}{,}{0}\right]{,}\left[{"F"}{,}{0}{,}{0}{,}{0.95000000}\right]\right]$ (1)

Compute the 2-RDM from the parametric 2-RDM method in the double-zeta ("dz") basis set

 >
 > $\mathrm{d2}\left[1,1,1,1\right];$
 ${1.99978160}$ (2)
 >