exercises:2016_uzh_cmest:path_optimization_neb
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exercises:2016_uzh_cmest:path_optimization_neb [2016/10/20 19:28] – [Visualize the trajectory] tmueller | exercises:2016_uzh_cmest:path_optimization_neb [2020/08/21 10:15] (current) – external edit 127.0.0.1 | ||
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Create a plot for this energy curve. | Create a plot for this energy curve. | ||
+ | |||
+ | ====== Vibrational analysis ====== | ||
+ | |||
+ | To verify whether the point at the highest energy is actually a transition state, we will be doing a vibrational analysis. | ||
+ | |||
+ | First identify the bead with the highest energy (see exercise above) and create a new XYZ file named '' | ||
+ | |||
+ | Use the following input file and the same command as above (with different input and output file names of course) to generate the analysis. | ||
+ | |||
+ | <code - ethane_TS_va.inp> | ||
+ | &GLOBAL | ||
+ | PROJECT ethane_TS_va | ||
+ | RUN_TYPE NORMAL_MODES | ||
+ | PRINT_LEVEL MEDIUM | ||
+ | &END GLOBAL | ||
+ | |||
+ | & | ||
+ | METHOD Quickstep | ||
+ | &DFT | ||
+ | BASIS_SET_FILE_NAME | ||
+ | POTENTIAL_FILE_NAME | ||
+ | |||
+ | & | ||
+ | PERIODIC XYZ | ||
+ | &END POISSON | ||
+ | & | ||
+ | SCF_GUESS ATOMIC | ||
+ | EPS_SCF 1.0E-7 | ||
+ | MAX_SCF 300 | ||
+ | &END SCF | ||
+ | & | ||
+ | & | ||
+ | &END XC_FUNCTIONAL | ||
+ | &END XC | ||
+ | &END DFT | ||
+ | |||
+ | &SUBSYS | ||
+ | &CELL | ||
+ | ABC 12. 12. 12. | ||
+ | PERIODIC XYZ | ||
+ | &END CELL | ||
+ | & | ||
+ | & | ||
+ | &END | ||
+ | COORD_FILE_FORMAT xyz | ||
+ | COORD_FILE_NAME | ||
+ | &END | ||
+ | &KIND H | ||
+ | ELEMENT H | ||
+ | BASIS_SET DZVP-MOLOPT-GTH | ||
+ | POTENTIAL GTH-PBE-q1 | ||
+ | &END KIND | ||
+ | &KIND C | ||
+ | ELEMENT C | ||
+ | BASIS_SET DZVP-MOLOPT-GTH | ||
+ | POTENTIAL GTH-PBE-q4 | ||
+ | &END KIND | ||
+ | &END SUBSYS | ||
+ | &END FORCE_EVAL | ||
+ | |||
+ | & | ||
+ | NPROC_REP 1 | ||
+ | DX 0.01 | ||
+ | FULLY_PERIODIC | ||
+ | |||
+ | & | ||
+ | &END | ||
+ | & | ||
+ | &END | ||
+ | & | ||
+ | &EACH | ||
+ | REPLICA_EVAL 1 | ||
+ | &END | ||
+ | &END | ||
+ | &END | ||
+ | &END | ||
+ | </ | ||
+ | |||
+ | Once this run completes, you should find a file '' | ||
+ | |||
+ | Now we are going to use the application //molden// (which you can load using '' | ||
+ | |||
+ | < | ||
+ | $ molden ethane_TS_va-VIBRATIONS-1.mol | ||
+ | </ | ||
+ | |||
+ | Click the //Norm. Mode// checkbox in the //Molden Control// window to list all the modes. What is the lowest frequency you get? By clicking on it you can visualize it. | ||
+ | |||
+ | The presence of a negative (imaginary) mode means that it is actually a transition state (and not stable). | ||
+ | |||
+ | Now repeat the same steps presented here for the bead with the lowest energy. What is now the first frequency you get in the list? Is this geometry stable? | ||
+ | |||
+ | Please note: while you should get only 18 different frequencies you get 21 instead. That means that 3 frequencies are global rotations instead of modes in the molecule and should be ignored when looking for negative frequencies to identify whether a conformer is stable or not. |
exercises/2016_uzh_cmest/path_optimization_neb.1476991695.txt.gz · Last modified: 2020/08/21 10:15 (external edit)