Multiscale calculation functionality

[hklem]

Enable multiscale calculation setups in gaussian and orca. Would require qprep arguments defining layer atoms and layer charge/mult. Code sections will depend on if program is gaussian or orca. Setting up input for gaussian oniom calculation is a bit more involved than that for orca, because gaussian will not automatically detect link atoms, unlike orca. So that information will need to be added into the gaussian input file text. https://gaussian.com/oniom/
Example gaussian ONIOM input:

ONIOM(B3LYP/6-31G(d,p):UFF) Opt

2-layer ONIOM optimization

0 1 0 1 0 1 #Charge/spin for entire molecule (real system), model system-high level & model-low
F -1.041506214819 0.000000000000 -2.126109488809 M
F -2.033681935634 -1.142892069126 -0.412218766901 M
F -2.033681935634 1.142892069126 -0.412218766901 M
C -1.299038105677 0.000000000000 -0.750000000000 M H 4
C 0.000000000000 0.000000000000 0.000000000000 H
H 0.000000000000 0.000000000000 1.100000000000 H
O 1.125833024920 0.000000000000 -0.650000000000 H