Review Reports

Round 1

Reviewer 1 Report

Please see the attached report.

Comments for author File: Comments.pdf

Author Response

We thank the reviewer for the suggestions and critical comments. Please see the attached file for reply to reviewers comments

Author Response File: Author Response.pdf

Reviewer 2 Report

This work shows an extensive DFT study of the isomers of Al2C4H2, some of which present non-classical configurations, such as planar tetracoordinated carbon and alulminium, as well as an analysis of their geometrical and electronic structures and their dynamic properties. Overall, the paper is well written, the selected DFT functional is adequate as well as the basis set used, the analysis of the electronic structure and chemical bonding by means of different methodologies is well done and complements the characterization of these structures. I consider that the article is suitable for publication, after considering the following (most of them minor) issues:

1) Please clarify the expression " elemental position" in line 63.

2) In line 65, the authors mention that the primary concern is to find the geometries of the ptC configurations, however, unless the number of atoms is very large, these geometries could even be created by hand. It is possible that the authors are referring to finding all isomers, not just the ptC ones, which is in most cases the most time consuming part of this type of research. Please clarify this

3) In line 77, the n in AlnC-, should be a subscript.

4) In line 86, I recommend specifying when referring to planar tetracoordinate or planar pentacoordinate carbon or boron isomers and not just "planar tetracoordinate isomers".

5) On line 88, it seems that the reference 52, does not correspond to the work of BAl4Mg, please check this

6) In line 110, at the end of the introduction, I recommend that the authors explain in more detail why the Al2C4H2 system has been specifically selected for the exploration of its isomers, it seems to me that it lacks connection with the previous paragraph, and instead is more related to ref 37 and works related to hydrogen storage.

7) Regarding the methodology, the authors should explain in more detail the process of generating the possible isomers prior to their geometric optimization, are they being constructed manually? or is some stochastic algorithm being used to explore the possible configurations?

8) Regarding molecular dynamics, why a simulation time of 1000fs (1ps) has been selected? It seems to me that this is too short a simulation time to really observe any isomerization process that might occur. Perhaps longer simulations or at a higher temperature should be considered, in order to be able to observe the possible transformations that may occur in a shorter simulation time.

Author Response

We thank the reviewer for the suggestions and critical comments. Please see the attached file for the reply to reviewer's comments

Author Response File: Author Response.pdf