SciPost Submission Page
Manifold curvature and Ehrenfest forces with a moving basis
by Jessica F. K. Halliday, Emilio Artacho
This Submission thread is now published as
Submission summary
Authors (as Contributors):  Emilio Artacho · Jessica Halliday 
Submission information  

Preprint link:  scipost_202110_00031v1 
Date accepted:  20211115 
Date submitted:  20211019 17:22 
Submitted by:  Artacho, Emilio 
Submitted to:  SciPost Physics 
Ontological classification  

Academic field:  Physics 
Specialties: 

Approach:  Theoretical 
Abstract
Known force terms arising in the Ehrenfest dynamics of quantum electrons and classical nuclei, due to a moving basis set for the former, can be understood in terms of the curvature of the manifold hosting the quantum states of the electronic subsystem. Namely, the velocitydependent terms appearing in the Ehrenfest forces on the nuclei acquire a geometrical meaning in terms of the intrinsic curvature of the manifold, while Pulay terms relate to its extrinsic curvature.
Published as SciPost Phys. 12, 020 (2022)
Author comments upon resubmission
Please find here the revised paper. We have addressed the points raised by the referees and yourself. As stated in our earlier replies to the referees, we amend the paper to include the clarifications requested, plus the ones that make clear in the paper what the referees were asking. We hope it is now acceptable for publication and will be happy to send the source material for processing.
Yours
Emilio Artacho
List of changes
The uploaded paper contains all changes marked in red. Namely:
 page 2 after eq 1: Clarification on N_n referring to number of nuclei, while the R_j refer to all their coordinates (j=1 .. 3N_n)
 page 2 after eq 2: the timedependent Omega space is always a subspace of the infinite dimensional ambient Hilbert space.
 page 3 1st par: clarification it could be done for orthonormalised bases, but numerically inconvenient, hence leaving general formalism.
 page 3 before eq 5: better definition of f(r) and of vector r. And of vector v as an instantaneous nuclear velocity.
 Section 2.3 divided into two subsections, 2.3.1 and 2.3.2, given that the first one had grown, and so becoming clearer.
 Subsection 2.3.1. (page 4) now includes connection with geometric phases (and cites, added to references).
 page 5 before eq. 9: reminder and citation for covariant derivative of Hamiltonian tensor, towards clarifying eq. 9
 page 5 above Pulay forces: clearer definition of adiabatic states chi^a_mu
 page 5 after eq 10: Clarifying relation between Eq. 10 and the following one
 page 5 after last eq: reminder of Omega in ambient Hilbert space
 Page 5 end (last red bit): adding for clarification on why for a flat Omega space Pulay terms don't appear
 page 6 before conclusions; clarification on extrinsic curvature sufficient for nonzero Pulay even if not intrinsic.
 page 6 end of par 1: add brief mention of gauge field interpretation analogous to geometricphase theory.
 page 6 last par of conclusions: remark on the question raised by the editor. Reference added.
More equations were numbered in this version, for handles on new clarifying text (new eq numbers)
Submission & Refereeing History
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Reports on this Submission
Anonymous Report 1 on 2021111 (Invited Report)
 Cite as: Anonymous, Report on arXiv:scipost_202110_00031v1, delivered 20211101, doi: 10.21468/SciPost.Report.3775
Report
The Authors of the Manuscript titled "Manifold curvature and Ehrenfest forces with a moving basis" have addressed all the points suggested in my initial report.
The similarities and differences between their formalism and the "gauge theory of molecular physics" of Koizumi, Hiroyasu, et al. have been discussed and Section 2.4 clarified.
I particularly appreciate the Authors' comment about the possible orthonormalisation of the basis set. That comment and the new conclusions further clarify the scope of their work, especially in view of numerical applications.
Claudio Attaccalite on 20211102 [id 1901]
In order to make the Referee/Editorial Process more transparent I put in this comment the additional questions I asked to the authors:
1) Does this new formulation will help practical calculations with moving basis? In the sense, I saw different calculations in the past that were obligated to add additional fictitious orbitals to achieve convergence.
2) Does this new formulation will help this convergence? and second will this new formulation allow to device better integrators for the the realtime dynamics?
the reply to these question is included in the new submission and I'm satisfied of the authors response.