Exact orientational thermodynamics of multipole rank pairs: a two-valued low-temperature heat-capacity law, with new data for 28 rank pairs (L = 2-24) and 29 real molecule pairs
- 1Hunan Institute of Engineering
Abstract
New results and new data reported in this work. This paper reports a primary data set and the law it yields, not a survey of the literature. (i) Orientational partition functions π(π¦) and low-temperature interaction heat capacities πΎ = πΆπ£/ππ΅ are computed for 28 multipole rank pairs spanning πΏ = π +π = 2 to πΏ = 24, each entry obtained by up to three mutually independent numerical routes β the large-π¦ tail of the thermal coupling function, the exact fluctuation formula, and the sublevel-volume exponent β and each with the coupling-minimum structure measured independently of the exponent. (ii) The exact second-moment identity is verified by direct quadrature for nine rank pairs to a maximum relative deviation of 6.8 Γ 10β14. (iii) Zero-parameter predictions β dominant channel, coupling scale and freezing temperature πβ β are given for 29 real molecule pairs (H2O, NH3, CO2, C2H4, CH4, BF3, CH3I, SF6, among others), and split them into the two low-temperature classes. (iv) A negative result is reported rather than omitted: the widely used singleparameter universality of the thermal coupling function Ξ¦ππ(π¦) is falsified, with relative deviations up to 47%. (v) The orientation average is reduced exactly to a three-dimensional integral and the kernel is obtained from a three-term recurrence valid at any rank, which removes the monomial-expansion ceiling of the earlier πΏ β€ 16 version. Every number quoted is tabulated in the main text (Tables 1, 2, 2a-2c, 3, 4) and in the Supporting Information (S1-S12), and the complete machine-readable data and code are openly archived (Zenodo DOI 10.5281/zenodo.23086356).
Related
- pGM5P-26: A Polarizable Gaussian Multipole Water Model with Transferable Temperature-Dependent Thermodynamics.
- A dimension staircase for orientational heat capacity: nature skips the 3/2 rung
- Temperature and Irrigation-Frequency Treatments Modulate Phytochemical Profiles and Antioxidant Capacity in Guzmania stenostachya and Werauhia macrochlamys
- Multipole splats for optimized and inverted effective potentials
- Fully Atomistic Vibrational Free Energy of Molecular Crystals Using Distributed Multipole Moments
BibTeX
@misc{lin2026exact,
title = {{Exact orientational thermodynamics of multipole rank pairs: a two-valued low-temperature heat-capacity law, with new data for 28 rank pairs (L = 2-24) and 29 real molecule pairs}},
author = {Fuxing Lin},
howpublished = {ChemRxiv},
year = {2026},
month = oct,
doi = {10.26434/chemrxiv.15010099/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010099/v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Exact orientational thermodynamics of multipole rank pairs: a two-valued low-temperature heat-capacity law, with new data for 28 rank pairs (L = 2-24) and 29 real molecule pairs
AU - Fuxing Lin
PY - 2026
DA - 2026/10/08
PB - ChemRxiv
DO - 10.26434/chemrxiv.15010099/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15010099/v1
AB - New results and new data reported in this work. This paper reports a primary data set and the law it yields, not a survey of the literature. (i) Orientational partition functions π(π¦) and low-temperature interaction heat capacities πΎ = πΆπ£/ππ΅ are computed for 28 multipole rank pairs spanning πΏ = π +π = 2 to πΏ = 24, each entry obtained by up to three mutually independent numerical routes β the large-π¦ tail of the thermal coupling function, the exact fluctuation formula, and the sublevel-volume exponent β and each with the coupling-minimum structure measured independently of the exponent. (ii) The exact second-moment identity is verified by direct quadrature for nine rank pairs to a maximum relative deviation of 6.8 Γ 10β14. (iii) Zero-parameter predictions β dominant channel, coupling scale and freezing temperature πβ β are given for 29 real molecule pairs (H2O, NH3, CO2, C2H4, CH4, BF3, CH3I, SF6, among others), and split them into the two low-temperature classes. (iv) A negative result is reported rather than omitted: the widely used singleparameter universality of the thermal coupling function Ξ¦ππ(π¦) is falsified, with relative deviations up to 47%. (v) The orientation average is reduced exactly to a three-dimensional integral and the kernel is obtained from a three-term recurrence valid at any rank, which removes the monomial-expansion ceiling of the earlier πΏ β€ 16 version. Every number quoted is tabulated in the main text (Tables 1, 2, 2a-2c, 3, 4) and in the Supporting Information (S1-S12), and the complete machine-readable data and code are openly archived (Zenodo DOI 10.5281/zenodo.23086356).
ER -