I found the dipoles of CO2 calculated by Quantum ESPRESSO as :
Computed dipole along edir(3) :
Elec. dipole 0.3112 Ry au, 0.7909 Debye
Ion. dipole 0.8137 Ry au, 2.0683 Debye
Dipole 41.9812 Ry au, 106.7055 Debye
Dipole field 0.5025 Ry au,
I assumed the third value is the sum of the electronic and ionic contributions.
The input and output files are attached herewith.
Since CO2 is non-polar molecule (with polar bonds), shouldn't the total dipole moment be zero?
Let me male my question specific
What is eopreg? How can I choose its value?
After modifying the input I got relatively better value. But I do not, still, what should be the value of eopreg? I assigned its value in the input after some try-and-error.
Dear Endale,
I am rather puzzled by your question and your input/output files. As a symmetric molecule CO2 has a 0 dipole moment (no dipole moment). It has a quadrupole moment because of the charge distribution. Of course you can induce the dipole moment by the external electric field, but I guess this is not you wanted to compute. Your molecule is linear and distributed on the Z (e3) axis. The number you computed is also puzzling. You apparently added a saw like electric field and obtained some kind of response. Before you start asking questions again you should study Espresso input file structure:
https://www.quantum-espresso.org/Doc/INPUT_PW.html
Bog
Dear Boguslaw
Thank you for the explanation.
Actually, this is my first practice for dipole moment calculation (though I work with QE for the last two years). Hence I want to check if I can get zero dipole moment for CO2. I believe this will help me to know how correct my inputs are.
My final target is doing this calculation for relatively complex molecules.
Really sorry if my approach is not correct.
Please help me in how to assign the value of eopreg.
With Regards
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