Screened range separation hybrid

How To
#1

Dear All, I am trying to use sRSH functional for my calculations in solid phase, but am unable to find any specific example/keywords related to it in the QChem manual. I have already optimally-tuned the molecule in the gas phase but am unsure about how to proceed from here to get the excited state values in the solid state. Any hint would be helpful. Thank you

#2

There is a section in the manual on this. I attach a screenshot from the latest version.

Screen Shot 2024-03-27 at 7.46.43 AM
Screen Shot 2024-03-27 at 7.46.43 AM1570×806 178 KB

Also discussed in this paper of mine (which is what led me to write the clarifying paper in the manual), see Section 2.2:
https://pubs.acs.org/doi/10.1021/acs.jpcc.0c07932
Lastly, there is a sample job with some extensive comments, which ships with Q-Chem. It is called srsh_pcm.in

#3

Thank you so much for your reply. Could you if possible send me this sample job that you have mentioned. It will be a great help.

#4

Here it is. If you find where Q-Chem is installed on your system (call it $QC), there should be a directory $QC/samples that contains a large number of sample jobs, divided into sub-directories. Searching through these for certain keywords can be a good way to see how something is used.

$comment
Screened RSH (SRSH) sample on pyridine, using PCM
Whereas for LRC versions of RSH, the coefficient of long-range HFX is set to 1.0,
in SRSH it is set to 1/eps where eps is the dielectric constant.

E_{XC}^{SRSH}= \alpha E_{F_x}^{SR}+(1-\alpha) E_{DF_x}^{SR}+ 1/\epsilon E_{F_x}^{LR}+(1-1/\epsilon )E_{DF_x}^{LR}+E_{DF_C} 

Define E_{DF_x}^{LR} \equiv  E_{DF_x} - E_{DF_x}^{SR}

E_{XC}^{SRSH}= \alpha E_{F_x}^{SR} + 1/\epsilon E_{F_x}^{LR} + \beta E_{DF_x}^{SR} + (1-1/\epsilon)E_{DF_x}+ E_{DF_C}
$end

$rem
Exchange              gen
Basis                 6-311+G(d,p)
Lrc_DFT               true
Omega                 255
Omega2                255
HF_LR                 83             ! a+b = 1/e (*1000)
HF_SR                 200 
SRC_DFT               2
solvent_method        pcm
$end
 
$xc_functional
C PBE           1.0
X PBE           0.92                  ! 1-(a+b)=1-1/e
X HF            0.2                   ! a
X wPBE         -0.117                 ! b
$end
 
$pcm
Theory           CPCM
Method           SWIG
Solver           Inversion
HeavyPoints      194
HPoints          194
Radii            Bondi
vdwScale         1.2
$end

$solvent
Dielectric       12.03
$end

$molecule
0  1
          N      -0.0107200000    -0.0024600000     1.6599200000
          C       0.0000000000     0.0000000000    -1.3825300000
          C       0.0000000000     1.1395800000     0.7203900000
          C       0.0000000000    -1.1395800000     0.7203900000
          C       0.0000000000    -1.1955500000    -0.6713100000
          C       0.0000000000     1.1955500000    -0.6713100000
          H       0.0000000000     0.0000000000    -2.4676700000
          H      -0.0012000000     1.9636800000     1.3184400000
          H       0.0190700000    -2.1779600000     1.3120800000
          H       0.0000000000    -2.1535800000    -1.1794500000
          H       0.0000000000     2.1535800000    -1.1794500000
$end
#5

Thank you. It helped a lot.