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As known, small HCl–water nanoclusters display a particular dissociation behaviour, whereby at least four water molecules are required for the ionic dissociation of HCl. In this work, we examine how intermolecular interactions promote the ionic dissociation of such nanoclusters. To this end, a set of 45 HCl–water nanoclusters with up to four water molecules is introduced. Energy decomposition analysis based on absolutely localized molecular orbitals (ALMO-EDA) is employed in order to study the importance of frozen interaction, dispersion, polarization, and charge-transfer for the dissociation. The vertical ALMO-EDA scheme is applied to HCl–water clusters along a proton-transfer coordinate varying the amount of spectator water molecules. The corresponding ALMO-EDA results show a clear preference for the dissociated cluster only in the presence of four water molecules. Our analysis of adiabatic ALMO-EDA results reveals a push–pull mechanism for the destabilization of the HCl bond based on the synergy between forward and backward charge-transfer.
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This content will become publicly available on March 1, 2026
Uncoupled fragment electric-field response functions: An accelerated model for the polarization energy in energy decomposition analysis of intermolecular interactions
Energy decomposition analysis (EDA) has become an important tool to relate electronic structure calculations to physically meaningful contributions. The second generation of the absolutely localized molecular orbitals (ALMO)-EDA accounts for polarization with a well- defined basis set limit using truncated virtual orbitals, namely fragment electric-field response functions (FERF). In this work, we introduce a hessian-free uncoupled FERF (uFERF) al- ternative that has very similar accuracy and is 8-10 times faster to evaluate. Furthermore, we investigate the use of monopole uFERFs (response to scaled nuclear charges) for inter-molecular interactions and establish their role in strong ion-neutral interactions.
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- Award ID(s):
- 2313791
- PAR ID:
- 10633065
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Chemical Physics Letters
- Volume:
- 862
- Issue:
- C
- ISSN:
- 0009-2614
- Page Range / eLocation ID:
- 141825
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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