Xt - Understanding Dipole Moment Components in Rigid and Non-Rigid Molecules

In summary, the conversation discusses the concept of the dipole moment vector in relation to rigid and non-rigid molecules. The question is posed about how the dipole moment vector changes when dealing with non-rigid molecules and the possibility of using expectation values. The concept of a rigid molecule is explained and the use of equilibrium position to determine the axis is suggested. The conversation ends with a mention of "Sayvez conditions" and a thank you to the participants.
  • #1
Konte
90
1
Hi everybody,

I want to ask a question about the dipole moment vector ##\vec{d}##, with components expressed in the molecule-fixed axis. By permuting identical nuclei that compose a rigid molecule, I know how ##d_x##, ##d_y##, ##d_z## change.
But when dealing with non-rigid molecule, I no longer know how to direct the molecule fixed- axis?

Thank you everybody.

Konte
 
Physics news on Phys.org
  • #2
Could you work with expectation values?
 
  • #3
Jilang said:
Could you work with expectation values?
How? What does you mean?

Konte.
 
  • #4
In molecular mechanics, what is meant by rigid is usually the assumption that the molecule only rotates in space without any vibration or at least vibrates with very small amplitude. In reality of course the molecule vibrates and hence the concept of rigid molecule no longer applies however for some low vibrational quantum numbers where the vibrational eigenfunction is more localized around the equilibrium position, you can take the equilibrium position to determine the axis.
 
  • #5
Look out for "Sayvez conditions".
 
  • Like
Likes Konte
  • #6
Thank you guys for your answer.
 

Related to Xt - Understanding Dipole Moment Components in Rigid and Non-Rigid Molecules

1. What is a dipole moment and why is it important in chemistry?

A dipole moment is a measure of the separation of positive and negative charges within a molecule. It is important in chemistry because it helps us understand the polarity of a molecule, which is crucial in determining its physical and chemical properties.

2. How is the dipole moment of a molecule calculated?

The dipole moment of a molecule is calculated by multiplying the magnitude of the charge on each atom by the distance between them. This can be represented mathematically as μ = q × r, where μ is the dipole moment, q is the charge, and r is the distance.

3. What are the different components of a dipole moment?

A dipole moment has two components: magnitude and direction. The magnitude is the strength of the dipole moment, while the direction is the direction in which the positive and negative charges are separated.

4. How do the dipole moment components differ in rigid and non-rigid molecules?

In rigid molecules, the dipole moment components are fixed and do not change. In non-rigid molecules, the dipole moment components can change due to molecular vibrations or rotations.

5. How does understanding dipole moment components help in predicting molecular properties?

Understanding dipole moment components can help predict a molecule’s polarity, which is important in determining its solubility, boiling point, and other physical and chemical properties. It can also be used to predict the strength of intermolecular forces between molecules.

Similar threads

I How to recalculate Berry phase dipole moments (jumps over time)?
    • Quantum Physics
Replies
5
Views
1K
A Calculating the interaction potential between 2 molecules
    • Atomic and Condensed Matter
Replies
3
Views
654
Why is a current ring approx a magnetic dipole from very far off?
    • Introductory Physics Homework Help
Replies
7
Views
296
I Two molecules with different polarizability in an EM field
    • Electromagnetism
Replies
4
Views
934
Effect of different magnetic fields on a magnetic dipole
    • Introductory Physics Homework Help
Replies
25
Views
321
I Derivative of the retarded vector potential
    • Electromagnetism
Replies
1
Views
822
Molecular symmetry group of non-rigid molecules
    • Chemistry
Replies
4
Views
2K
Computing molecular symmetry group for non rigid molecules
    • Chemistry
Replies
2
Views
2K
A Transition dipole moment - polarized absorption
    • Atomic and Condensed Matter
Replies
5
Views
2K
Derivation of ideal magnetic dipole field strength
    • Electromagnetism
Replies
1
Views
783

Hot Threads

Recent Insights

Back
Top