I am trying to find energy of a donor-acceptor-donor system while scnning about the dihedral angle between the donor and accptor. But I am ending up with the error: "Error imposing constraints"
Can anyone help me with this issue? I have attached log my file and below is my input file. Thank you so much!
%mem = 50GB
%NProcShared = 16
%chk = checkpoint.chk
#n opt=modredundant CAM-B3LYP/6-31G(d,p) EmpiricalDispersion=GD3
PDI scan with opt gr state and both An 180 degree 10 steps
0 1
C -2.28570100 -1.72847800 0.16597600
C -1.44648700 0.50797900 -0.30588000
C -2.77551300 0.99175300 -0.35108700
C -3.84792300 0.10983800 -0.11257300
C -3.59485500 -1.20374600 0.18061300
H -4.42953200 -1.85564100 0.41224000
C -1.21208500 -0.89415000 -0.15924800
C 0.16967200 -1.36515900 -0.36912600
C 0.47515300 -2.68346100 -0.66919400
C 1.23975400 -0.42451700 -0.26322300
C 1.79687900 -3.13318900 -0.75569500
C 2.83719300 -2.26994500 -0.51454600
C 2.57031200 -0.90791500 -0.26506000
C -3.03677800 2.34713500 -0.63500200
C -1.99103100 3.20505200 -0.86923100
C -0.67165600 2.75774700 -0.73844000
C -0.37426300 1.44637300 -0.40318900
C 1.00090000 0.98000000 -0.14739600
C 2.06395000 1.82088600 0.19515000
C 3.37254100 1.29837200 0.25237700
C 3.63568500 -0.01920400 -0.01443300
H -2.20607300 4.23528200 -1.12720200
H -0.31800500 -3.39597100 -0.83312700
C -5.24558500 0.59468200 -0.14950800
C -4.42684500 2.84821900 -0.70983900
N -5.44051500 1.95330700 -0.36225100
C -6.82868700 2.41062800 -0.48395100
H -7.38134400 2.01406800 0.36856700
H -6.79502000 3.49641200 -0.41815700
C -7.49630400 1.97274000 -1.78919400
H -8.43658100 2.52680500 -1.88682500
H -7.75844700 0.91184300 -1.72272300
C -6.64836600 2.20010500 -3.03778200
H -6.21282800 3.20233900 -3.02532600
H -7.28216800 2.12034700 -3.93256900
O -5.54638400 1.30484100 -3.12361900
H -5.89870900 0.40663900 -3.11680900
O -6.19747400 -0.15239800 0.00485700
O -4.68356800 3.99247600 -1.04010300
C 4.22817600 -2.77445900 -0.53978900
C 5.03671500 -0.49840800 -0.00285600
H 2.01830100 -4.16935500 -0.98331200
H 4.20034700 1.95462300 0.49611200
N 5.23691400 -1.85950900 -0.23291400
O 4.49821500 -3.93158600 -0.80644500
O 5.97957200 0.24580600 0.19739700
C 6.61921700 -2.34489700 -0.25389100
C 7.23156100 -2.22830100 -1.64372800
C 8.66253300 -2.72768500 -1.67456500
O 9.13776300 -2.57676400 -2.99909300
H 10.04765600 -2.89087400 -3.03400500
H 6.63800500 -2.81047700 -2.35431600
H 7.21516900 -1.18250700 -1.96360300
H 6.59755700 -3.38447100 0.07307900
H 7.17828700 -1.74756500 0.46639300
H 9.27156000 -2.15036400 -0.96089400
H 8.69399100 -3.78111500 -1.35389400
C 0.14599100 2.92979300 3.85794500
C 0.75886000 2.58158500 2.69399800
C 1.29968600 3.57313800 1.81460400
C 1.19278100 4.94719500 2.21085200
C 0.54149500 5.26941900 3.44144100
C 0.02882700 4.29586700 4.23943000
C 1.92000300 3.25346200 0.59162500
C 1.72364200 5.94147800 1.39389200
C 2.35507000 5.63642800 0.19166100
C 2.45511600 4.26754200 -0.22430500
C 3.06338400 3.99581500 -1.49166100
H 3.12321700 2.97042700 -1.83638600
C 3.55956400 5.00059400 -2.26459000
C 3.48240300 6.35498800 -1.83469800
C 2.89516300 6.65942200 -0.64674200
H -0.25608400 2.15917200 4.50751500
H 0.84665300 1.53646900 2.42453900
H 0.46578300 6.31533100 3.72312500
H -0.46561100 4.55233100 5.17034400
H 1.64164000 6.98042900 1.70134100
H 4.01710700 4.76999100 -3.22086100
H 3.88783300 7.14041900 -2.46362100
H 2.82045400 7.68977700 -0.31233400
C -3.64049700 -6.28518600 -1.85433600
C -3.09798800 -6.57540700 -0.64178000
C -2.58510400 -5.54295000 0.20214000
C -2.66618700 -4.17949600 -0.23498900
C -3.22712700 -3.92269700 -1.52707300
C -3.69735400 -4.93636600 -2.30463800
C -1.99752900 -5.83362300 1.42995400
C -2.15730000 -3.15591100 0.58567000
C -1.58049000 -3.46094000 1.83326100
C -1.49206600 -4.82983600 2.25145200
C -0.88501000 -5.13693600 3.50824500
H -0.82263800 -6.17902800 3.80681900
C -0.39697400 -4.15382500 4.30997800
C -0.49573600 -2.79275500 3.90591600
C -1.06674500 -2.45876600 2.71679300
H -1.92983900 -6.86854000 1.75401800
H -4.02473600 -7.07790700 -2.48741400
H -3.03863200 -7.60150100 -0.29157800
H -3.26936400 -2.90143400 -1.88665400
H -4.11720500 -4.71786800 -3.28091800
H 0.06397200 -4.39883400 5.26094800
H -0.11334300 -2.01456700 4.55831800
H -1.14124600 -1.41735600 2.42948900
H 0.12586600 3.46692800 -0.89651000
D 88 1 7 8 S 10 18.0
D 60 64 19 18 S 10 18.0
Nita Ghosh
I understand the challenge you are facing with constraining the dihedral angle in your geometry optimization calculations in Gaussian 16.
The key error appears to be "Error imposing constraints" which likely indicates an issue with how the dihedral angle is being defined. My recommendation would be to try changing the dihedral definition from being based on atom numbers (D 88 1 7 8 S 10 18.0) to explicitly listing the atoms (D C1-C2-C3-C4 S 10 18.0).
Defining dihedrals based on atom names rather than numbers can help avoid ambiguities, especially in larger systems. Additionally, double-check that the atom sequence and dihedral angle value you are constraining match your intentions for the scan.
Should these modifications still result in constraint errors, we can look into tweaking optimizer settings and potentially using redundant internal coordinates rather than Cartesian coordinates. There are also some excellent Gaussian user forums we could consult with example input files.
Please let me know if you would like to discuss further strategies for successfully performing constrained geometry optimizations in Gaussian. Overcoming these kinds of issues is part of the learning process as we advance computational chemistry techniques. Wishing you all the best on your research!
#CompChem #QC #Gaussian
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