Instantaneous dipole moment and orbitals

[asphy]

TL;DR

How can idea of instantaneous dipole moment for atoms like, for example hydrogen be consistent with idea of orbitals.

Hi. I have got question as in title. How can idea of instantaneous dipole moment for atoms like, for example hydrogen be consistent with idea of orbitals? At my level of knowledge London dispersion forces are derived taking into account Bohr model of atom. But we know today that this model is not correct. If it would be correct I understand that at each time electron is at some point at radius at some angle and there is dipole moment at this time from nucleus to electron at orbit. But how is it possible to atom like hydrogen have instantanous dipole moment if around nucleus "is" orbital so electron doesn't have position and, what is the most important - probability of finding electron around nucleus at some radius in whole angles is the same, so vector sum of negative charge contributions from each angle goes to zero. For me it means that existence of dipole moment is impossible because there isn't any negative resultant negative charge. At the end. I understand dipole moment in, for example HCl molecule but in H atom no. So I would be grateful if someone explain me this or give link to some paper that explain this phenomena.

 

[anuttarasammyak]

In case there exists external E field, permanent or instantaneous by fluctuation, atomic dipole moment would appear to lower the system energy.

 

[DrDu]

When talking about London forces, you always need at least two atoms. Their dipole dipole interaction involves the product of the dipole moment operators d1 and d2 of the two atoms. While the expectation value of each of these operator vanishes, that of their product is non-vanishing, given that <0 | d1 d2 | 0> can be expanded in a sum involving excited states i, <0| d1 | i> <i| d2| 0> .