Showing posts with label mixed basis set. Show all posts
Showing posts with label mixed basis set. Show all posts

09 October 2023

676. Mixed basis set with gaussian when continuing from a chk-file

 I'm currently working with computations on paramagnetic species, so being able to read the geometry from the chk-file is important in order to avoid having to define the multiplicities of all the segments of the molecule. 

I also can't use def2-tzvp for the entire molecule since the .chk files during freq cals become too big for my current storage allocation (>500 gb). The work is exploratory at the moment, so compromises are OK.

I first run a calc with a small basis set:


%nprocshared=28
%Mem=24gb
%Chk=I1_hs.chk
#P uPBE1PBE/def2svp 5D 7F Punch=(MO) Pop=() guess=(fragment=8,only) nosymm

intermediate 1, pbe0/def-svp.

0 9 -2 1 0 1 0 1 -3 1 -1 1 0 1 4 4 2 6 
S(fragment=1)          -7.953777000    -0.003180000    -2.912460000
O(fragment=1)          -3.008379000    -0.432531000    -1.322496000
...

--Link1--
%nprocshared=28
%mem=24gb
%chk=I1_hs.chk
#P uPBE1PBE/chkbasis 5D 7F Opt=() SCRF=(PCM,Solvent=water)  Punch=(MO) Pop=() guess=read geom=allcheck nosymm
I then want to optimise the structure obtained at def2-svp using a mixed basis set where I use def2-tzvp for all the cobalt centres, and def2-svp for the organic bits.

%nprocshared=28
%Mem=24gb
%oldChk=I1_hs.chk
%chk=I1_hs_tzvp.chk
#P uPBE1PBE/genecp 5D 7F Opt=() SCRF=(PCM,Solvent=water)  Punch=(MO) Pop=() guess=read geom=allcheck nosymm

C H N O 0
def2svp
****

Co 0
def2tzvp
****

Co 0
def2



The basis set definitions are in blue, and the ecp bit is in red.