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11.5 Effective Fragment Potential Method

11.5.8 Calculation of User-Defined EFP Potentials

(May 7, 2024)

User-defined EFP parameters can be generated in “MAKEFP” job in gamess; see the gamess manual for details. The user-defined parameter (.efp) files should be located in the working directory; the name of the .efp file should match exactly the name of the fragment, for example, beginning of the cl_ion.efp parameter file should look like:

 $cl_ion
 Comment line
 COORDINATES (BOHR)
  ....

The EFP potential generation begins by determining an accurate structure for the fragment (EFP is the frozen-geometry potential, so the fragment geometry will remain the same in all subsequent calculations). We recommend MP2/cc-pVTZ level of theory.

11.5.8.1 Generating EFP Parameters Using gamess

EFP parameters can be generated in gamess using a “MAKEFP” job (RUNTYP = MAKEFP in gamess). For EFP parameters calculations, 6-311++G(3df,2p) basis set is recommended. Originally Stone’s distributed multipole analysis is recommended for non-aromatic compounds (bigexp = 0 in the group $stone); optionally, one may decrease the basis set to 6-31G* or 6-31+G* for generation of electrostatic multipoles and screening parameters. (To prepare such a “mixed” potential, one has to run two separate MAKEFP calculations in larger and smaller bases, and combine the corresponding parts of the potential). In aromatic compounds, one must either use numerical grid for generation of multipoles (bigexp = 4.0) or use 6-31G* basis with standard analytic DMA, which is recommended. The MAKEFP job produces (usually in the scratch directory) the .efp file containing all the necessary EFP parameters. See the gamess manual for further details. Below are examples of a gamess input file for RUNTYP = MAKEFP, for water and for benzene.

GAMESS input example for water.

 $contrl units=angs local=boys runtyp=makefp coord=cart icut=11 $end
 $system timlim=99999 mwords=200 $end
 $scf soscf=.f. diis=.t. conv=1.0d-06 $end
 $basis gbasis=n311 ngauss=6 npfunc=2 ndfunc=3 nffunc=1
   diffs=.t. diffsp=.t. $end
 $stone
   bigexp=0.0
 $end
 $damp ifttyp(1)=3,2 iftfix(1)=1,1 thrsh=500.0 $end
 $dampgs
h3=h2
bo31=bo21
 $end
 $makefp chtr=.f. disp7=.f. $end
 $data
 water h2o (geometry: mp2/cc-pvtz)
 c1
o1 8.0  0.0000  0.0000  0.1187
h2 1.0  0.0000  0.7532 -0.4749
h3 1.0  0.0000 -0.7532 -0.4749
 $end
GAMESS input example for benzene.

 $contrl units=bohr local=boys runtyp=makefp coord=cart icut=11 $end
 $system timlim=99999 mwords=200 $end
 $scf soscf=.f. diis=.t. conv=1.0d-06  $end
 $basis gbasis=n311 ngauss=6 npfunc=2 ndfunc=3 nffunc=1
   diffs=.t. diffsp=.t. $end
 $stone
   bigexp=4.0
 $end
 $damp ifttyp(1)=3,2 iftfix(1)=1,1 thrsh=500.0 $end
 $dampgs
c6=c5
c2=c1
c3=c1
c4=c1
c5=c1
c6=c1
h8=h7
h9=h7
h10=h7
h11=h7
h12=h7
bo32=bo21
bo43=bo21
bo54=bo21
bo61=bo21
bo65=bo21
bo82=bo71
bo93=bo71
bo104=bo71
bo115=bo71
bo126=bo71
 $end
 $makefp chtr=.f. disp7=.f. $end
 $data
benzene c6h6 (geometry: mp2/cc-pvtz)
c1
c1     6.0    1.3168      -2.2807       0.0000
c2     6.0    2.6336       0.0000       0.0000
c3     6.0    1.3168       2.2807       0.0000
c4     6.0   -1.3168       2.2807       0.0000
c5     6.0   -2.6336      -0.0000       0.0000
c6     6.0   -1.3168      -2.2807       0.0000
h7     1.0    2.3386      -4.0506       0.0000
h8     1.0    4.6772       0.0000       0.0000
h9     1.0    2.3386       4.0506       0.0000
h10    1.0   -2.3386       4.0506       0.0000
h11    1.0   -4.6772       0.0000       0.0000
h12    1.0   -2.3386      -4.0506       0.0000
 $end