excited states and combination bands

[Dhiksha Sharma]

I am new to NWChem and currently performing VSCF vibrational frequency calculations using double-hybrid functionals. I was able to successfully compute first overtones using the iexcite keyword. However, I am unsure how to correctly set up the input to calculate and print combination bands (e.g., ν1+ν2) and excited vibrational states.

Here is my current input that works for overtones:

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echo
start ktzvpp_hcooh8

geometry units angstrom
 symmetry group cs
 C                    0.00083644     0.42247010     0.00000000
 H                   -0.38019081     1.44665705     0.00000000
 O                   -1.02968805    -0.44152184     0.00000000
 O                    1.16057294     0.11546650     0.00000000
 H                   -0.65666948    -1.33480956     0.00000000
end

basis spherical
  O library DEF2-TZVPP
  H library DEF2-TZVPP
  C library DEF2-TZVPP
end

DRIVER
 GMAX 0.000015
 GRMS 0.00001
 XMAX 0.00006
 XRMS 0.00004
end

MP2
   freeze atomic
end

dft
  xc HFexch 0.53 becke88 0.47 lyp 0.73 mp2 0.27
  dftmp2
  direct
  grid lebedev 99 14
end

vscf
 ngrid 12
 iexcite 2
end

task dft vscf numerical
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