I try to understand the log file generated after optimization of a molecular structure in the presence of external field. I used the following line in the gjf file: # opt=Z-matrix b3pw91/6-311++g(d,p) Field=x-5 nosymm. I have several questions regarding the log file:
(1) There is such information in the resulting file regarding the dipole moment: "Dipole moment (field-independent basis, Debye):" So, the data of the dipole moment vector included in this file give the information only about the permament dipole moment of the geometry or does it also include the induced dipole moment by external field?
(2) The energy of the optimized geometry, e.g., "HF=-1145.2712779" is the energy of the optimized geometry only or does it include also the contribution resulting from the interaction between dipole moment and the external field (the scalar multiplication of dipole moment vector and field vector)?
(3) after optimization in the Z-matrix, I noticed that the dipole moment vector starts in the (0,0,0) coordinate of the cartesian system, which is a different scenario from the optimization in cartesian coordinates. Is this outcome correct?
I appreciate Your help.
Hi,
I believe the answer to your first two questions is yes, they include the external electric field effects. You can simply compare the dipole moments and energies by removing the Field keyword and crosscheck.
For the third question, I guess since you mentioned "nosymm" keyword during your optimization (which one should while applying an oriented external electric field) the the dipole moment vector starts in the (0,0,0) coordinate. The input orientation is fixed therefore and it is correct I guess.
hi Andrzej Nowok . In brief, please be advised of the following: 1) This will depend on how the structure of the molecule you are trying to optimize is responding to changes in its spatial geometry under the influence of elenctic/magnetic field you applied in the simulation. Generally, you need to optimize the structure under the applied field, and then you run Vibrational Circular Dichroism (VCD) and Raman spectra calculations along with Vibrational–Rotational Coupling Analysis to determine value and direction of the dipole moment - you may refer to my publication for more information - Article Magnetic Field Induced Alignment of Macroradical Epoxy for E...
2) to answer this question, please run the optimization with again without Filed = x-5, and how this affects both dipole and the optimization value. Again, alignment will depend on the intensity of the field. I have discussed this in the cited above publication, too. 3) I have no answer because this will depend on your system of coordination (i.e., global vs local). I hope you find this useful- Badges
- Science topic
- Similar topics
- Chemistry
- Theoretical Chemistry