Hi,
I am using SF-TDDFT, and I want to know which method helps to find the minimum energy pathway from S0min and S1min to the conical intersection using the qchem 5.3 version.
Usually, when I was using Gaussian, I used a relaxed scan.
Hi John,
Thanks
I read about Minimum energy crossing points from qchem manual. I have taken optimized coordinates from CIS_STATE_DERIVATIVE=1 and given the input for the MECP job.
$molecule
0 3
optimized coordinates
$end
$rem
BASIS = GEN
PURECART = 1
EXCHANGE = omegaB97X-D
omega = 156
GUI = 2
JOB_TYPE = OPTIMIZATION
MECP_OPT = true
MECP_METHODS = penalty_function
SCF_CONVERGENCE = 8
MAX_SCF_CYCLES = 500
MAX_CIS_CYCLES = 500
SPIN_FLIP = true
CIS_TRIPLETS = false
unrestricted = true
CIS_N_ROOTS = 4
MECP_STATE1 = [0,1]
MECP_STATE2 = [0,2]
CIS_S2_THRESH = 120
GEOM_OPT_MAX_CYCLES = 400
MEM_TOTAL = 40000
SOLVENT_METHOD = PCM
$end
$solvent
DIELECTRIC 32.613000
OPTICALDIELECTRIC 1.765709
$end
$basis
H 0
S 3 1.00
13.0107010 0.19682158D-01
1.9622572 0.13796524
0.44453796 0.47831935
S 1 1.00
0.12194962 1.0000000
P 1 1.00
0.8000000 1.0000000
C 0
S 5 1.00
1238.4016938 0.54568832082D-02
186.29004992 0.40638409211D-01
42.251176346 0.18025593888
11.676557932 0.46315121755
3.5930506482 0.44087173314
S 1 1.00
0.40245147363 1.0000000
S 1 1.00
0.13090182668 1.0000000
P 3 1.00
9.4680970621 0.38387871728D-01
2.0103545142 0.21117025112
0.54771004707 0.51328172114
P 1 1.00
0.15268613795 1.0000000
D 1 1.00
0.8000000 1.0000000
N 0
S 5 1.00
1712.8415853 -0.53934125305D-02
257.64812677 -0.40221581118D-01
58.458245853 -0.17931144990
16.198367905 -0.46376317823
5.0052600809 -0.44171422662
S 1 1.00
0.58731856571 1.0000000
S 1 1.00
0.18764592253 1.0000000
P 3 1.00
13.571470233 -0.40072398852D-01
2.9257372874 -0.21807045028
0.79927750754 -0.51294466049
P 1 1.00
0.21954348034 1.0000000
D 1 1.00
1.0000000 1.0000000
$end
output file:
486 -748.7851636851 1.92e-05
487 -748.7851495815 1.90e-05
488 -748.7851467361 1.89e-05
489 -748.7851248561 1.87e-05
490 -748.7851874297 1.92e-05
491 -748.7851691548 1.89e-05
492 -748.7848326330 2.13e-05
493 -748.7846045948 3.05e-05
494 -748.7849675961 1.62e-05
495 -748.7850312615 1.60e-05
496 -748.7850339468 1.67e-05
497 -748.7850339522 1.68e-05
498 -748.7850247431 1.63e-05
499 -748.7850682172 1.53e-05
500 -748.7851392080 1.55e-05
gen_scfman_exception: SCF failed to converge
Q-Chem fatal error occurred in module libgscf/gen_scfman/gen_scfman_main.C, line 218:
Error in gen_scfman
It looks like the SCF procedure has problems converging. You can check if, in the previous 400 steps, the error is also of the order of e-05. Sometimes this happens, but there are several strategies to improve the SCF convergence, for example, the Maximum Overlap Method (MOM).
Other strategies are discussed in the Q-Chem manual in this chapter: 4.5.1 Introduction‣ 4.5 Converging SCF Calculations ‣ Chapter 4 Self-Consistent Field Ground-State Methods ‣ Q-Chem 6.0 User’s Manual
I suggest you read through the chapter and check which option helps you with this.
You can also try something like this:
| gen_scfman true | |
|---|---|
| gen_scfman_hybrid_algo true | |
| gen_scfman_algo_1 diis | |
| gen_scfman_iter_1 50 | |
| gen_scfman_conv_1 5 | |
| gen_scfman_algo_2 GDM | |
| gen_scfman_iter_2 50 | |
| gen_scfman_conv_2 5 | |
| gen_scfman_algo_3 SGM | |
| gen_scfman_iter_3 200 | |
| gen_scfman_conv_3 5 |
Thank you so much, Giudetti and Jimkress. Your suggestions work.