Issue Reproducing Polarizability Curve from Q-Chem Paper

Questions
#1

Hello,

I am trying to reproduce the (TOC) curve from this Q-Chem paper: https://onlinelibrary.wiley.com/doi/10.1002/anie.202312078
As a first step, I ran a single-point calculation at a large H–H distance to check whether I can correctly recover both the energy and the polarizability of the H₂ dimer.

Regarding the energy, everything looks fine — I obtain: -0.99867553 a.u.

However, the polarizability I get looks quite off:

               ======================================================= 
               ===                                                 ===
               ===                 Polarizability (a.u.)           ===
               ===                                                 ===
               ======================================================= 

   =================================================================================
   =   Frequency:            0.00000000 a.u.    =           0.00000000 eV          =
   =                                            =           0.00000000 x 10^-8 Hz  =
   =   Wavenumber:           0.00000000 cm^(-1)                                    =
   =================================================================================

      ISOTROPIC:      8.65319129          ANISOTROPIC:      0.45031596

      Trace =        25.95957388
      Full Tensor:

                      8.50308598           -0.00000000           -0.00000000
                     -0.00000000            8.50308597           -0.00000000
                     -0.00000000           -0.00000000            8.95340194

This value does not match the expected polarizability, and when performing a PES scan, the polarizability curve I obtain does not resemble the Gaussian-like shape shown in the paper. In particular, at large separations, the polarizability tends to a constant value as I increase the H–H distance, instead of decreasing with distance as shown in your results.

I feel like I might be missing something essential to properly reproduce the results from your work.

For reference, here is my input:

$molecule
   0  1
   H  0.000   0.000   0.0 
   H  0.000   0.000  4.0
$end

$rem
   UNRESTRICTED     =  true
   METHOD           =  hf  
   BASIS            =  aug-cc-pvdz
   SCF_ALGORITHM    =  diis_gdm
   MAX_DIIS_CYCLES  =  1
   SCF_GUESS        =  gwh 
   SCF_GUESS_MIX    =  2
   MOPROP           = 2
$end

Thank you!

PS: The following code input was done using Q-chem 5.0 since my university does not provide the newest one

#2

With the current version of the code (pre-release Q-Chem v. 6.3), I get the same output that you show, when I run your input file. You could test this by applying a finite field and looking at the change in the dipole moment, which is another way to define the polarizability. Or you could try contacting the original authors to ask how they did the calculations.