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arxiv: 2606.31417 · v1 · pith:HZNRRBHPnew · submitted 2026-06-30 · ❄️ cond-mat.mtrl-sci · physics.comp-ph

Side-Chain Tuning of Thermal-Expansion Crossover in Metal-Organic Frameworks

Pith reviewed 2026-07-01 04:45 UTC · model grok-4.3

classification ❄️ cond-mat.mtrl-sci physics.comp-ph
keywords metal-organic frameworksthermal expansionnegative thermal expansionside-chain engineeringentropy crossoverMOF-5alkoxy functionalization
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The pith

Alkoxy side-chain length in MOF-5 controls a tunable crossover from positive to negative thermal expansion through competing entropy terms.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper establishes that grafting alkoxy chains of varying lengths onto the linkers of MOF-5 produces distinct thermal expansion behaviors. Chains with two or fewer carbons yield steady contraction as temperature rises, while chains of three or more carbons produce expansion at low temperatures that switches to contraction at higher temperatures. The switch arises because longer chains access more conformational shapes at modest heat, creating steric pressure that enlarges the lattice, whereas higher heat strengthens framework vibrations that favor contraction. Adjusting the fraction of linkers that carry these chains further allows the overall expansion coefficient to be set to negative, near-zero, or positive values inside chosen temperature intervals.

Core claim

The central claim is that an entropy-driven PTE-to-NTE crossover occurs in alkoxy-functionalized MOF-5 when side-chain length n reaches three or more carbons: short chains (n ≤ 2) produce monotonic NTE while longer chains generate low-temperature PTE from side-chain conformational entropy and high-temperature NTE from enhanced framework vibrational entropy, with continuous regulation of the thermal expansion coefficient achieved by varying the concentration of functionalized linkers.

What carries the argument

Alkoxy side-chain length n (number of carbon atoms) and its concentration on the MOF-5 linkers, which shift the balance between conformational entropy of the chains and vibrational entropy of the framework modes.

If this is right

  • Short side chains (n ≤ 2) produce only negative thermal expansion across the studied temperature range.
  • Chains with n ≥ 3 produce positive expansion at low temperature that crosses to negative expansion at higher temperature.
  • Diluting the fraction of side-chain-functionalized linkers allows the net expansion coefficient to be set continuously to negative, zero, or positive within selected windows.
  • The crossover temperature itself shifts with side-chain length and concentration.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The same side-chain strategy might be tested in other cubic MOFs to see whether the entropy competition generalizes beyond MOF-5.
  • One could check whether the near-zero expansion windows remain stable under modest pressure or guest-molecule loading.
  • Device concepts that exploit the temperature-dependent sign change for thermal switches or compensators become conceivable once the concentration tuning is validated experimentally.

Load-bearing premise

The classical and path-integral molecular dynamics simulations plus lattice dynamics correctly identify conformational and vibrational entropy as the dominant competing mechanisms without substantial force-field or sampling errors.

What would settle it

Experimental measurement of the thermal expansion coefficient versus temperature for MOF-5 samples with n=3 side chains at several concentrations, showing either no PTE-to-NTE crossover or no continuous tuning to near-zero values, would falsify the central claim.

Figures

Figures reproduced from arXiv: 2606.31417 by Penghua Ying, Wei Qiu.

Figure 1
Figure 1. Figure 1: FIG. 1. Structural models of pristine and alkoxy [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Side-chain tuning of thermal-expansion crossover in [PITH_FULL_IMAGE:figures/full_fig_p003_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. String-tension origin of NTE. (a) Volume-dependent [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5. Composition-programmed thermal expansion over [PITH_FULL_IMAGE:figures/full_fig_p005_5.png] view at source ↗
read the original abstract

Achieving continuous control over macroscopic thermal expansion remains a fundamental challenge in solid-state physics. Using classical and path-integral molecular dynamics alongside lattice dynamics at near-\emph{ab initio} accuracy, we report an entropy-driven thermal-expansion crossover from positive (PTE) to negative thermal expansion (NTE) in alkoxy-functionalized MOF-5, an archetypal metal-organic framework (MOF). We demonstrate that this non-linear response is continuously tunable via the alkoxy side-chain length, quantified by the number of carbon atoms $n$ grafted onto the archetypal cubic MOF-5 framework: systems with short chains ($n \le 2$) exhibit monotonic NTE, whereas longer chains ($n \ge 3$) trigger a pronounced PTE-to-NTE crossover. At low temperatures, thermal activation of longer side chains opens additional conformational states and generates steric pressure inside the pore, driving positive expansion through a gain in side-chain conformational entropy. Conversely, at elevated temperatures, the side chains enhance transverse linker fluctuations and strengthen the string-tension mechanism associated with low-frequency framework modes, causing structural contraction favored by framework vibrational entropy. Finally, by varying the concentration of side-chain-functionalized linkers, the thermal expansion coefficient can be continuously regulated to realize negative, near-zero, and positive thermal expansion within selected temperature windows. These results establish side-chain engineering as a practical route for programming macroscopic thermodynamic responses in MOFs.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The paper claims that alkoxy side-chain functionalization of MOF-5 produces an entropy-driven PTE-to-NTE thermal-expansion crossover tunable by chain length n (monotonic NTE for n≤2; crossover for n≥3) and by functionalized-linker concentration, with low-T positive expansion arising from side-chain conformational entropy and high-T contraction from enhanced framework vibrational entropy, as computed via classical and path-integral MD plus lattice dynamics.

Significance. If the reported mechanisms and tunability are robust, the work supplies a concrete design principle for programming thermal expansion in MOFs via side-chain engineering, which would be of clear interest for functional materials. The use of multiple simulation techniques (including path-integral MD) to separate conformational and vibrational contributions is a methodological strength.

major comments (2)
  1. [Methods / Simulation details] The central claim that longer side chains (n≥3) generate low-T PTE via conformational entropy while enhancing high-T NTE via vibrational entropy rests on the classical force-field description of side-chain dihedrals and pore steric interactions; however, no ab-initio validation of the key torsional barriers or non-bonded parameters is reported, leaving open the possibility that force-field errors shift or remove the crossover.
  2. [Results / Concentration series] The reported continuous tunability by varying the concentration of side-chain-functionalized linkers is load-bearing for the practical-application claim, yet the manuscript supplies no explicit mixing-rule validation or concentration-dependent sampling statistics to confirm that the entropy partition remains additive across compositions.
minor comments (2)
  1. [Abstract] The abstract states 'near-ab initio accuracy' for the lattice-dynamics component but does not specify the underlying electronic-structure method, basis set, or dispersion correction.
  2. [Figures] Figure captions and axis labels for the thermal-expansion coefficient vs. temperature plots should explicitly state the temperature window and error estimation method used.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the positive evaluation of the work's significance and for the detailed comments. We respond to each major comment below.

read point-by-point responses
  1. Referee: [Methods / Simulation details] The central claim that longer side chains (n≥3) generate low-T PTE via conformational entropy while enhancing high-T NTE via vibrational entropy rests on the classical force-field description of side-chain dihedrals and pore steric interactions; however, no ab-initio validation of the key torsional barriers or non-bonded parameters is reported, leaving open the possibility that force-field errors shift or remove the crossover.

    Authors: We agree that explicit ab-initio validation of the torsional barriers would strengthen the force-field results. The parameters are taken from established literature for MOF-5 and alkoxy groups, and the combination of classical MD, path-integral MD, and near-ab-initio lattice dynamics provides internal consistency checks on the reported mechanisms. Nevertheless, in the revised manuscript we will add DFT calculations of the key side-chain dihedral profiles to directly validate the barriers and non-bonded terms against the force field. revision: yes

  2. Referee: [Results / Concentration series] The reported continuous tunability by varying the concentration of side-chain-functionalized linkers is load-bearing for the practical-application claim, yet the manuscript supplies no explicit mixing-rule validation or concentration-dependent sampling statistics to confirm that the entropy partition remains additive across compositions.

    Authors: The concentration series was generated by direct simulation of mixed-linker supercells at several compositions. To address the concern, the revised manuscript will include (i) explicit verification that the mixing rules reproduce the pure-component limits and (ii) concentration-dependent error estimates from block averaging to confirm adequate sampling of the entropy contributions. revision: yes

Circularity Check

0 steps flagged

No circularity: claims rest on independent simulation outputs

full rationale

The paper reports simulation results (classical MD, path-integral MD, lattice dynamics) that identify an entropy-driven PTE-to-NTE crossover tunable by side-chain length n and linker concentration. No equations, fitted parameters, or self-citations are presented that would reduce the reported crossover temperature, sign change, or tunability to a definition or prior fit by construction. The central claims derive from computed free-energy contributions and mode analysis rather than any of the enumerated circular patterns. This is the expected self-contained case for a simulation-driven study.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

Abstract-only review; ledger is limited to assumptions visible in the text.

axioms (1)
  • domain assumption Classical and path-integral molecular dynamics plus lattice dynamics at near-ab initio accuracy correctly capture side-chain conformational entropy and framework vibrational entropy.
    Invoked to explain the temperature-dependent crossover and tunability.

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Reference graph

Works this paper leans on

43 extracted references · 43 canonical work pages · 1 internal anchor

  1. [1]

    Theorie des festen zustandes einatomiger elemente,

    Eduard Gr¨ uneisen, “Theorie des festen zustandes einatomiger elemente,” Annalen der Physik344, 257–306 (1912)

  2. [2]

    Negative thermal expansion from 0.3 to 1050 Kelvin in ZrW2O8,

    T. A. Mary, J. S. O. Evans, T. Vogt, and A. W. Sleight, “Negative thermal expansion from 0.3 to 1050 Kelvin in ZrW2O8,” Science272, 90–92 (1996)

  3. [3]

    Negative thermal expansion in zrw2o8 and hfw2o8,

    J. S. O. Evans, T. A. Mary, T. Vogt, M. A. Subrama- nian, and A. W. Sleight, “Negative thermal expansion in zrw2o8 and hfw2o8,” Chemistry of Materials8, 2809– 2823 (1996)

  4. [4]

    Pronounced negative thermal expan- sion from a simple structure: cubic scf3,

    Benjamin K. Greve, Keith L. Martin, Peter L. Lee, Peter J. Chupas, Karena W. Chapman, and An- gus P. Wilkinson, “Pronounced negative thermal expan- sion from a simple structure: cubic scf3,” Journal of the American Chemical Society132, 15496–15498 (2010)

  5. [5]

    The widespread occurrence of negative thermal expansion in zeolites,

    Philip Lightfoot, David A. Woodcock, Martin J. Maple, Luis A. Villaescusa, and Paul A. Wright, “The widespread occurrence of negative thermal expansion in zeolites,” Journal of Materials Chemistry8, 563–564 (1998)

  6. [6]

    Negative and positive anisotropic thermal expansion in 2D fullerene networks,

    Armaan Shaikh, Jiaqi Wu, and Bo Peng, “Negative and positive anisotropic thermal expansion in 2D fullerene networks,” Physical Review Letters135, 126103 (2025)

  7. [7]

    Ma- chine learning enables the discovery of 2D Invar and anti- Invar monolayers,

    Shun Tian, Ke Zhou, Wanjian Yin, and Yilun Liu, “Ma- chine learning enables the discovery of 2D Invar and anti- Invar monolayers,” Nature Communications15, 6977 (2024)

  8. [8]

    Chemical diversity for tailor- ing negative thermal expansion,

    Qiang Li, Kun Lin, Zhanning Liu, Lei Hu, Yili Cao, Jun Chen, and Xianran Xing, “Chemical diversity for tailor- ing negative thermal expansion,” Chemical Reviews122, 8438–8486 (2022)

  9. [9]

    Negative thermal expansion in the metal-organic framework ma- terial cu3(1,3,5-benzenetricarboxylate)2,

    Yue Wu, Atsushi Kobayashi, Gregory J. Halder, Vanessa K. Peterson, Karena W. Chapman, Nina Lock, Peter D. Southon, and Cameron J. Kepert, “Negative thermal expansion in the metal-organic framework ma- terial cu3(1,3,5-benzenetricarboxylate)2,” Angewandte Chemie International Edition47, 8929–8932 (2008)

  10. [10]

    Isotropic zero thermal expansion in sodalite crystals from 11 to 893 k,

    Youquan Liu, Xingxing Jiang, Maxim S Molokeev, Mikhail Plyaskin, Zhenhuang Su, Qianru Lin, Jie Sheng, Wen Wen, Xingyu Gao, MT Dove,et al., “Isotropic zero thermal expansion in sodalite crystals from 11 to 893 k,” Nature Chemistry , 1–8 (2026)

  11. [11]

    Unified theoretical framework for thermal expansion en- gineering in multilayer 2d materials,

    Yan Chen, Yixin Lin, Changsheng Feng, Kai Kang, Huichao Liu, Penghua Ying, Yang Yang, and Yilun Liu, “Unified theoretical framework for thermal expansion en- gineering in multilayer 2d materials,” Extreme Mechanics Letters , 102474 (2026)

  12. [12]

    Structural origins of thermal expansion behavior in 2d materials,

    Yang Yang, Guangya Li, Yixin Lin, Yan Chen, Hongxi- ang Zong, Xiangdong Ding, Xun-Li Wang, and Jun Sun, “Structural origins of thermal expansion behavior in 2d materials,” Acta Materialia , 121956 (2026)

  13. [13]

    Reticular synthesis and the design of new materials,

    Omar M Yaghi, Michael O’Keeffe, Nathan W Ockwig, Hee K Chae, Mohamed Eddaoudi, and Jaheon Kim, “Reticular synthesis and the design of new materials,” Nature423, 705–714 (2003)

  14. [14]

    Origin of the exceptional nega- tive thermal expansion in metal-organic framework-5 Zn 4 O (1, 4-benzenedicarboxylate) 3,

    Wei Zhou, Hui Wu, Tanner Yildirim, Jeffrey R Simpson, and AR Hight Walker, “Origin of the exceptional nega- tive thermal expansion in metal-organic framework-5 Zn 4 O (1, 4-benzenedicarboxylate) 3,” Physical Review B 78, 054114 (2008)

  15. [15]

    Negative thermal expansion materials: technological key for control of thermal expansion,

    Koshi Takenaka, “Negative thermal expansion materials: technological key for control of thermal expansion,” Sci- ence and Technology of Advanced Materials13, 013001 (2012)

  16. [16]

    Isotropic negative thermal expan- sion,

    Arthur W. Sleight, “Isotropic negative thermal expan- sion,” Annual Review of Materials Science28, 29–43 (1998)

  17. [17]

    Origin of the invar effect in iron-nickel alloys,

    Mark van Schilfgaarde, I. A. Abrikosov, and B. Johans- son, “Origin of the invar effect in iron-nickel alloys,” Na- ture400, 46–49 (1999)

  18. [18]

    Tuning of thermal expansion properties of a mixed-ligand MOF by ligand variation,

    Tapaswini Sethi, Debarati Bhattacharya, and Dina- bandhu Das, “Tuning of thermal expansion properties of a mixed-ligand MOF by ligand variation,” CrystEng- Comm25, 3356–3360 (2023)

  19. [19]

    Tuning thermal expansion in metal- organic frameworks using a mixed linker solid solution approach,

    Samuel J. Baxter, Andreas Schneemann, Austin D. Ready, Pavithra Wijeratne, Angus P. Wilkinson, and Nicholas C. Burtch, “Tuning thermal expansion in metal- organic frameworks using a mixed linker solid solution approach,” Journal of the American Chemical Society 141, 12849–12854 (2019). 7

  20. [20]

    Negative thermal expansion de- sign strategies in a diverse series of metal–organic frame- works,

    Nicholas C Burtch, Samuel J Baxter, Jurn Heinen, Ash- ley Bird, Andreas Schneemann, David Dubbeldam, and Angus P Wilkinson, “Negative thermal expansion de- sign strategies in a diverse series of metal–organic frame- works,” Advanced Functional Materials29, 1904669 (2019)

  21. [21]

    Controlling thermal expansion: a metal–organic frameworks route,

    Salvador RG Balestra, Rocio Bueno-Perez, Said Hamad, David Dubbeldam, A Rabdel Ruiz-Salvador, and Sofia Calero, “Controlling thermal expansion: a metal–organic frameworks route,” Chemistry of Materials28, 8296– 8304 (2016)

  22. [22]

    Tuning the negative thermal expansion behavior of the metal– organic framework Cu3BTC2 by retrofitting,

    Christian Schneider, David Bodesheim, Michael G Ehrenreich, Valentina Crocell` a, J´ anos Mink, Roland A Fischer, Keith T Butler, and Gregor Kieslich, “Tuning the negative thermal expansion behavior of the metal– organic framework Cu3BTC2 by retrofitting,” Journal of the American Chemical Society141, 10504–10509 (2019)

  23. [23]

    Experimental indications of superionic behaviour in iron hydride under earth’s core conditions,

    Yoshihiro Nagaya, Yusuke Okazaki, Haruhiko Dekura, and Kenji Ohta, “Experimental indications of superionic behaviour in iron hydride under earth’s core conditions,” Nature Geoscience , 1–6 (2026)

  24. [24]

    Assessing negative thermal expansion in mesoporous metal–organic frameworks by molecular simulation,

    Jack D Evans, Johannes P D¨ urholt, Stefan Kaskel, and Rochus Schmid, “Assessing negative thermal expansion in mesoporous metal–organic frameworks by molecular simulation,” Journal of materials chemistry A7, 24019– 24026 (2019)

  25. [25]

    Feynman and Albert R

    Richard P. Feynman and Albert R. Hibbs,Quantum Me- chanics and Path Integrals(McGraw-Hill, New York, 1965)

  26. [26]

    Study of an F center in molten KCl,

    M. Parrinello and A. Rahman, “Study of an F center in molten KCl,” The Journal of Chemical Physics80, 860– 867 (1984)

  27. [27]

    Nuclear quantum effects enter the mainstream,

    Thomas E. Markland and Michele Ceriotti, “Nuclear quantum effects enter the mainstream,” Nature Reviews Chemistry2, 0109 (2018)

  28. [28]

    Highly effi- cient path-integral molecular dynamics simulations with gpumd using neuroevolution potentials: Case studies on thermal properties of materials,

    Penghua Ying, Wenjiang Zhou, Lucas Svensson, Esm´ ee Berger, Erik Fransson, Fredrik Eriksson, Ke Xu, Ting Liang, Jianbin Xu, Bai Song,et al., “Highly effi- cient path-integral molecular dynamics simulations with gpumd using neuroevolution potentials: Case studies on thermal properties of materials,” The Journal of Chemi- cal Physics162, 064109 (2025)

  29. [29]

    Efficient stochas- tic thermostatting of path integral molecular dynamics,

    Michele Ceriotti, Michele Parrinello, Thomas E Mark- land, and David E Manolopoulos, “Efficient stochas- tic thermostatting of path integral molecular dynamics,” The Journal of chemical physics133, 124104 (2010)

  30. [30]

    Local vibrational mechanism for negative thermal expansion: A combined neutron scat- tering and first-principles study,

    Vanessa K Peterson, Gordon J Kearley, Yue Wu, Anibal Javier Ramirez-Cuesta, Ewout Kemner, and Cameron J Kepert, “Local vibrational mechanism for negative thermal expansion: A combined neutron scat- tering and first-principles study,” Angewandte Chemie 122, 595–598 (2010)

  31. [31]

    Structurally Triggered Breakdown of the Phonon Gas Model in Crystalline Metal-Organic Frameworks

    Penghua Ying, Ting Liang, Yun Chen, Yan Chen, Shiyun Xiong, Zheyong Fan, Jianbin Xu, and Yilun Liu, “Struc- turally triggered breakdown of the phonon gas model in crystalline metal-organic frameworks,” arXiv preprint arXiv:2604.03783 (2026)

  32. [32]

    Neuroevolution machine learning poten- tials: Combining high accuracy and low cost in atomistic simulations and application to heat transport,

    Zheyong Fan, Zezhu Zeng, Cunzhi Zhang, Yanzhou Wang, Keke Song, Haikuan Dong, Yue Chen, and Tapio Ala-Nissila, “Neuroevolution machine learning poten- tials: Combining high accuracy and low cost in atomistic simulations and application to heat transport,” Physical Review B104, 104309 (2021)

  33. [33]

    Frustrated flexibility in metal- organic frameworks,

    Roman Pallach, Julian Keupp, Kai Terlinden, Louis Frentzel-Beyme, Marvin Kloß, Andrea Machalica, Ju- lia Kotschy, Suresh K Vasa, Philip A Chater, Chris- tian Sternemann,et al., “Frustrated flexibility in metal- organic frameworks,” Nature Communications12, 4097 (2021)

  34. [34]

    Visualization and analysis of atomistic simulation data with OVITO–the Open Visu- alization Tool,

    Alexander Stukowski, “Visualization and analysis of atomistic simulation data with OVITO–the Open Visu- alization Tool,” Modelling and Simulation in Materials Science and Engineering18, 015012 (2010)

  35. [35]

    Gpumd 4.0: A high-performance molecular dynamics package for ver- satile materials simulations with machine-learned po- tentials,

    Ke Xu, Hekai Bu, Shuning Pan, Eric Lindgren, Yongchao Wu, Yong Wang, Jiahui Liu, Keke Song, Bin Xu, Yi- fan Li, Tobias Hainer, Lucas Svensson, Julia Wiktor, Rui Zhao, Hongfu Huang, Cheng Qian, Shuo Zhang, Zezhu Zeng, Bohan Zhang, Benrui Tang, Yang Xiao, Zi- han Yan, Jiuyang Shi, Zhixin Liang, Junjie Wang, Ting Liang, Shuo Cao, Yanzhou Wang, Penghua Ying, ...

  36. [36]

    Combining the D3 dispersion correction with the neuroevolution machine- learned potential,

    Penghua Ying and Zheyong Fan, “Combining the D3 dispersion correction with the neuroevolution machine- learned potential,” Journal of Physics: Condensed Mat- ter36, 125901 (2024)

  37. [37]

    A consistent and accurate ab initio parametrization of density functional dispersion correc- tion (DFT-D) for the 94 elements H-Pu,

    Stefan Grimme, Jens Antony, Stephan Ehrlich, and Helge Krieg, “A consistent and accurate ab initio parametrization of density functional dispersion correc- tion (DFT-D) for the 94 elements H-Pu,” The Journal of Chemical Physics132, 154104 (2010)

  38. [38]

    Design and synthesis of an exception- ally stable and highly porous metal-organic framework,

    Hailian Li, Mohamed Eddaoudi, Michael O’Keeffe, and Omar M Yaghi, “Design and synthesis of an exception- ally stable and highly porous metal-organic framework,” Nature402, 276–279 (1999)

  39. [39]

    MOF-FF–A flexible first-principles de- rived force field for metal-organic frameworks,

    Sareeya Bureekaew, Saeed Amirjalayer, Maxim Tafipol- sky, Christian Spickermann, Tapta Kanchan Roy, and Rochus Schmid, “MOF-FF–A flexible first-principles de- rived force field for metal-organic frameworks,” physica status solidi (b)250, 1128–1141 (2013)

  40. [40]

    Elucidating negative thermal expansion in mof-5,

    Nina Lock, Yue Wu, Mogens Christensen, Lisa J. Cameron, Vanessa K. Peterson, Adam J. Bridgeman, Cameron J. Kepert, and Bo B. Iversen, “Elucidating negative thermal expansion in mof-5,” The Journal of Physical Chemistry C114, 16181–16186 (2010)

  41. [41]

    Metal-organic frameworks provide large negative thermal expansion behavior,

    Sang Soo Han and William A. Goddard, “Metal-organic frameworks provide large negative thermal expansion behavior,” The Journal of Physical Chemistry C111, 15185–15191 (2007)

  42. [42]

    A mathematical theory of communica- tion,

    C. E. Shannon, “A mathematical theory of communica- tion,” Bell System Technical Journal27, 379–423 (1948)

  43. [43]

    Method for esti- mating the configurational entropy of macromolecules,

    Martin Karplus and James N. Kushick, “Method for esti- mating the configurational entropy of macromolecules,” Macromolecules14, 325–332 (1981)