Hello, I am running an ALMO-EDA calculation (EDA2 = FALSE ) with COVP analysis in Q-Chem 6.4.0 on an intramolecular donor–acceptor system. The system is an anion radical with overall charge = −1 and multiplicity = 2. The fragments are defined as:
- Fragment 1 (biphenyl donor): charge = −1, multiplicity = 1
- Fragment 2 (cyclohexane-bridged naphthalene acceptor): charge = 0, multiplicity = 2
The fragment calculations appear to complete successfully, but the combined ALMO/SCF step fails to converge. Even after 500 SCF cycles, the energy oscillates substantially and does not approach convergence. Are there any recommended strategies (e.g., different SCF algorithms, level shifting, MOM, fragment spin assignments, or alternative initial guesses) that might improve convergence?
Any guidance would be greatly appreciated.
I am sharing my input file:
$molecule
-1 2
--
-1 1
C -1.06129 -1.38834 0.86231
C -1.98190 -1.06148 1.86571
C -3.34703 -1.22181 1.72370
C -3.93191 -1.74700 0.52666
C -2.98229 -2.07465 -0.49436
C -1.62636 -1.89482 -0.31843
C -5.33982 -1.94315 0.36842
C -6.30528 -1.42856 1.30030
C -7.65989 -1.63008 1.14386
C -8.18078 -2.36085 0.06121
C -7.25877 -2.87675 -0.86780
C -5.90213 -2.67817 -0.73052
H -1.58706 -0.68542 2.80563
H -3.98310 -0.97744 2.56764
H -3.33094 -2.45875 -1.44683
H -0.94728 -2.14944 -1.13083
H -5.97167 -0.83359 2.14390
H -8.34045 -1.20360 1.87851
H -9.24747 -2.51960 -0.05461
H -7.61867 -3.45740 -1.71521
H -5.24359 -3.12524 -1.46764
--
0 2
C 2.32828 0.55327 0.73990
C 3.14022 -0.66283 1.21121
C 2.49201 -1.30986 2.44774
C 0.95274 -1.19338 2.44486
C 0.43638 -1.18507 0.99897
C 0.89676 0.12823 0.31291
H 2.24035 1.22638 1.60094
H 4.16842 -0.36129 1.43352
H 3.20608 -1.38841 0.39265
H 2.78032 -2.36536 2.48920
H 2.88997 -0.84538 3.35602
H 0.65697 -0.26329 2.94853
H 0.52707 -2.01959 3.02108
H 0.94193 -2.01895 0.48127
H 0.85056 0.00134 -0.77325
H 0.20723 0.94229 0.55601
C 5.42748 5.25454 -1.92543
C 5.63946 4.63545 -3.17796
C 5.16711 3.37069 -3.40762
C 4.46289 2.66504 -2.40068
C 4.24634 3.28626 -1.14358
C 4.74769 4.59645 -0.93527
C 3.96033 1.35356 -2.60118
C 3.28298 0.70376 -1.60967
C 3.05491 1.31293 -0.34547
C 3.53656 2.57970 -0.13803
H 5.80357 6.25702 -1.75229
H 6.17540 5.16709 -3.95648
H 5.32350 2.89085 -4.36882
H 4.58268 5.07229 0.02641
H 4.11772 0.87232 -3.56151
H 2.90545 -0.29759 -1.78928
H 3.37548 3.06629 0.82024
$end
$rem
JOBTYPE EDA
EDA2 FALSE
METHOD wB97X-D
BASIS 6-31G**
PURECART 1112
FRGM_METHOD STOLL
FRGM_LPCORR ARS
SCF_PRINT_FRGM TRUE
EDA_COVP TRUE
EDA_PRINT_COVP TRUE
UNRESTRICTED TRUE
IANLTY 200
MAX_SCF_CYCLES 500
SCF_CONVERGENCE 8
SCF_ALGORITHM GDM
THRESH 14
$end
$plots
MOs
120 -13.2 10.6
91 -7.9 10.3
80 -8.4 7.4
12 0 0 0
96 97 98 99 100 101 95 96 97 98 99 100
$end