This manuscript presents a computational investigation of large neutral clusters containing sulfuric acid (SA), methanesulfonic acid (MSA), and amine bases (AM, MA, DMA), extending the cluster size up to 10 acid–base pairs (20 molecules). The study addresses an important topic in aerosol formation, and the reported structural and thermochemical data for large mixed-acid clusters could constitute a valuable contribution to the field, consistent with the scope of Aerosol Research. The manuscript addresses a timely and interesting topic, and the generation of large-cluster data is potentially valuable. However, the current version has substantial gaps in literature coverage, compositional sampling and data accessibility. A major revision is required to address these points. After thorough revision and careful technical editing, the manuscript could become a worthy contribution to Aerosol Research.

Major Comments

1. Lines 78–83 state that the synergistic effects of mixed acids remain poorly understood, but the manuscript does not cite or discuss the directly relevant work by Elm, 2022, Clusteromics III, which specifically reports that MSA can enhance cluster formation potential by up to ~20-fold and explicitly identifies the SA–MSA–DMA system as the most promising candidate for extension to larger sizes. This omission is critical and must be rectified. Johnson and Jen, 2023 provides experimental evidence for SA–MSA–base co-condensation and observes enhanced pathways involving SA–MSA–MA. This work should be incorporated as a benchmark for the chosen base systems. Baalbaki et al., Nature, 2026 reports that below –10 °C, MSA–NH3 nucleation can rival SA–NH₃, with clear SA–MSA synergy, and that under humid conditions MSA can drive growth near the kinetic limit. Even if this paper appeared after the current submission, it is highly relevant and must be discussed in the revised manuscript to situate the findings within the most recent experimental context.
2. The methodology only considers pure SA, pure MSA, and mixed clusters of the form (MSA)1(SA)n-1(base)n. As n increases from 2 to 10, the MSA mole fraction automatically decreases from 1/2 to 1/10. Under atmospherically relevant MSA:SA ratios of 100:1 or 1000:1, this single‑MSA substitution path cannot represent the likely cluster compositions that would dominate. More critically, it cannot answer whether acid synergy exists or what the preferred compositions are.
3. Lines 124–136 report training and validation set sizes and state “validation errors below 0.012 kcal mol⁻¹” without specifying whether this is MAE or RMSE, per‑cluster or per‑atom, and whether it applies to energies, forces, or both. No force error is given. This value is notably lower. The authors must clarify the metric and units, and verify that the reported accuracy is consistent with the referenced methodology.
4. The phrase “atmospherically relevant” requires more careful justification. The introduction cites typical MSA concentrations of 10⁵–10⁷ molecules cm⁻³, yet Figure 7 uses 10⁹ molecules cm⁻³. Similarly, AM at 10 ppb may be high for cold, pristine marine or polar environments. Provide explicit references for the chosen concentration ranges and include a sensitivity analysis or at least a discussion of how results would change under lower, more pristine conditions.
5. The Data Availability statement points only to the ACDB Articles/ root directory, without providing a dedicated subdirectory, version, submission hash, or DOI. Upon verification, the link does not uniquely identify the new structures and thermochemical data reported in this study. A direct, versioned dataset link with a citation is required.
6. The study does not directly compute particle sizes, formation rates, or observable particle numbers; it focuses on thermochemical properties of clusters up to 20 molecules. If the title emphasising “Formation and Growth” is retained, the manuscript should include size indicators (e.g., diameters) and some kinetic or dynamic support (e.g., evaporation rates, growth pathways). Alternatively, the title should be narrowed to reflect the actual content, such as “Stability and Composition of Large SA–MSA–Base Molecular Clusters”.

Technical Corrections 

Abstract, line 7: “methane sulfonic acid” → “methanesulfonic acid”.

Abstract, line 16: “a secondary species that participate” → “a secondary species that participates”.

Line 41: “2nm” → “2 nm”.

Line 43: “around ∼1.5 nm” – use either “around 1.5 nm” or “∼1.5 nm” (redundant).

Lines 47–48: Add parentheses before and after “Almeida et al. (2013)” and clarify whether “ten acid and base molecules” means ten molecules total or ten acid–base pairs.

Line 57: “marine environment” → “marine environments”.

Line 83: “up to n=10 acid-base molecules” → “up to n=10 acid–base pairs (20 molecules)”.

Lines 97–98: Revise “clusters of 1 to n=5” for clarity (e.g., “clusters with n = 1 to 5”).

Line 102: “improves finding global minimum” → “improves the likelihood of finding the global minimum”; use “global minima” when referring to several clusters.

Line 120: “as implement in SchNetPack” → “as implemented in SchNetPack”.

Lines 122–124: “model to performed excellently” → “model to perform well”; “structures ... was used” → “structures ... were used”.

Line 132: “as following” → “as follows”.

Line 145: “Equation (1) ... describe” → “describes”; remove the comma in “with a 100 cm⁻¹, threshold”.

Line 158: “as a function of molecules in the cluster” → “as a function of the number of molecules in the cluster”.

Lines 169–171 and throughout: Standardise spacing in kcal mol⁻¹ and all units (e.g., use non‑breaking thin spaces where appropriate).

Line 222: “MSA only affect” → “MSA only affects”.

Line 231: Remove “the” from “the our calculations”.

Figure 4: Reconcile 298Lmsa in the panels with 298Hmsa in the caption/text.

Line 246: “we see now role of MSA” – ambiguous; revise for clarity (likely a typo).

Line 252: “the DMA-containing cluster remain” → “clusters remain” (or “the DMA-containing clusters remain”).

Section 3.2.4 heading: Standardise capitalization and spacing in “High MSA–high SA”.

Figure 7 caption: Remove the comma in “molec., cm⁻³” and use “molecules cm⁻³” consistently.

Data availability: Replace the ACDB root link with a direct, versioned dataset link and citation.

References: Kirkby et al. (2011a, 2011b) appear to duplicate the same Nature article; Nadykto et al. (2014a, 2014b) also appear duplicated. Remove duplicates and retain single entries.

References: Cooley et al. (2023) and Cromar and Lazrak (2023) lack complete bibliographic information (e.g., volume, page numbers, or DOI); provide full details.