Nuclear quantum effects on the thermodynamic response functions of a polymorphic waterlike monatomic liquid

Liu, Yizhi; Sun, Gang; Eltareb, Ali; López, Gustavo E.; Giovambattista, Nicolás; Xu, Limei

doi:10.1103/physrevresearch.2.013153

“…For example, the temperature of maximum density and the glass transition temperature (T ) of H O and D O differ by 7–10 K, a clear sign of non-negligible NQE. Path-integral computer simulations of water-like models that have a LLCP clearly show that NQE can indeed shift the location of the LLCP as well as alter the shape and slope of the and maxima lines 47 , 48 . Interestingly, while experiments in glassy water have estimated differences in the location of the LLCP in H O and D O ( K, MPa) 49 , 50 , the issue of isotope effects on the location of the LLCP has not been explored in computational and theoretical studies.…”

Section: Introductionmentioning

confidence: 99%

Evidence of a liquid–liquid phase transition in H$$_2$$O and D$$_2$$O from path-integral molecular dynamics simulations

Eltareb

¹

,

López

²

,

Giovambattista

³

2022

Sci Rep

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We perform path-integral molecular dynamics (PIMD), ring-polymer MD (RPMD), and classical MD simulations of H$$_2$$ 2 O and D$$_2$$ 2 O using the q-TIP4P/F water model over a wide range of temperatures and pressures. The density $$\rho (T)$$ ρ ( T ) , isothermal compressibility $$\kappa _T(T)$$ κ T ( T ) , and self-diffusion coefficients D(T) of H$$_2$$ 2 O and D$$_2$$ 2 O are in excellent agreement with available experimental data; the isobaric heat capacity $$C_P(T)$$ C P ( T ) obtained from PIMD and MD simulations agree qualitatively well with the experiments. Some of these thermodynamic properties exhibit anomalous maxima upon isobaric cooling, consistent with recent experiments and with the possibility that H$$_2$$ 2 O and D$$_2$$ 2 O exhibit a liquid-liquid critical point (LLCP) at low temperatures and positive pressures. The data from PIMD/MD for H$$_2$$ 2 O and D$$_2$$ 2 O can be fitted remarkably well using the Two-State-Equation-of-State (TSEOS). Using the TSEOS, we estimate that the LLCP for q-TIP4P/F H$$_2$$ 2 O, from PIMD simulations, is located at $$P_c = 167 \pm 9$$ P c = 167 ± 9 MPa, $$T_c = 159 \pm 6$$ T c = 159 ± 6 K, and $$\rho _c = 1.02 \pm 0.01$$ ρ c = 1.02 ± 0.01 g/cm$$^3$$ 3 . Isotope substitution effects are important; the LLCP location in q-TIP4P/F D$$_2$$ 2 O is estimated to be $$P_c = 176 \pm 4$$ P c = 176 ± 4 MPa, $$T_c = 177 \pm 2$$ T c = 177 ± 2 K, and $$\rho _c = 1.13 \pm 0.01$$ ρ c = 1.13 ± 0.01 g/cm$$^3$$ 3 . Interestingly, for the water model studied, differences in the LLCP location from PIMD and MD simulations suggest that nuclear quantum effects (i.e., atoms delocalization) play an important role in the thermodynamics of water around the LLCP (from the MD simulations of q-TIP4P/F water, $$P_c = 203 \pm 4$$ P c = 203 ± 4 MPa, $$T_c = 175 \pm 2$$ T c = 175 ± 2 K, and $$\rho _c = 1.03 \pm 0.01$$ ρ c = 1.03 ± 0.01 g/cm$$^3$$ 3 ). Overall, our results strongly support the LLPT scenario to explain water anomalous behavior, independently of the fundamental differences between classical MD and PIMD techniques. The reported values of $$T_c$$ T c for D$$_2$$ 2 O and, particularly, H$$_2$$ 2 O suggest that improved water models are needed for the study of supercooled water.

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“…Using the TSEOS, one can estimate the LLCP location (ρ c , T c , P c ). The values of (ρ c , T c , P c ) for the case of q-TIP4P/F H 2 O, based on classical MD and PIMD simulations, are given in Table I and Interestingly, recent studies based on water-like monoatomic model liquids that exhibit a LLCP, show that including NQE has the effects of lowering T c and increasing P c , while leaving ρ c unaffected [47,48]. We also compare the volumes predicted by the TSEOS with the corresponding values obtained from our MD and PIMD simulations.…”

Section: Resultsmentioning

confidence: 99%

“…Overall, including NQE shifts the location of the LLCP, LLPT line, and maxima/minima lines towards lower temperatures (see also Ref. [47,48]). Consistent with the existence of a LLCP, our study shows the presence of loci of maxima in C P and κ T in the P-T phase diagram of q-TIP4P/F water.…”

Section: Diffusion Coefficientmentioning

confidence: 92%

“…We also performed extensive PIMD simulations of heavy water using the q-TIP4P/F shift considerably the location of the LLCP [47,48]. In particular, the differences in the relative values of (ρ c , P c , T c ) between q-TIP4P/F H 2 O and D 2 O are somewhat consistent with the predictions from experiments in glassy water (∆P c = 50 MPa, ∆T c = 10 K) [49,50] and with the relative location of the κ T -maximum at 1 bar [10].…”

Section: Diffusion Coefficientmentioning

confidence: 99%

“…For example, the temperature of maximum density and the glass transition temperature (T g ) of H 2 O and D 2 O differ by 7 − 10 K, a clear sign of non-negligible NQE. Path-integral computer simulations of water-like models that have a LLCP clearly show that NQE can indeed shift the location of the LLCP as well as alter the shape and slope of the C P (T ) and κ T (T ) maxima lines [47,48]. Interestingly, while experiments in glassy water have estimated differences in the location of LLCP in H 2 O and D 2 O (∆T c ≈ 10 K, ∆P c ≈ 50 MPa) [49,50], the issue of isotope effects on the location of the LLCP has not been explored in computational and theoretical studies.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Liquid-Liquid Phase Transition in Supercooled H2O and D2O: A Path-Integral Computer Simulation Study

Eltareb

¹

,

López

²

,

Giovambattista

³

2021

Preprint

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We perform path-integral molecular dynamics (PIMD) and classical MD simulations of H2O and D2O using the q-TIP4P/F water model over a wide range of temperatures and pressures. The density ρ(T), isothermal compressibility κT(T), and self-diffusion coefficients D(T) of H2O and D2O are in excellent agreement with available experimental data; the isobaric heat capacity CP(T) obtained from PIMD and MD simulations agree qualitatively well with the experiments. Some of these thermodynamic properties exhibit anomalous maxima upon isobaric cooling, consistent with recent experiments and with the possibility that H2O and D2O exhibit a liquid-liquid critical point (LLCP) at low temperatures and positive pressures. The data from PIMD/MD for H2O and D2O can be fitted remarkably well using the Two-State-Equation-of-State (TSEOS). Using the TSEOS, we estimate that the LLCP for q-TIP4P/F H2O, from PIMD simulations, is located at Pc = 167±9 MPa, Tc = 159±6 K, and ρc = 1.02±0.01 g/cm3. Isotope substitution effects are important; the LLCP location in q-TIP4P/F D2O is estimated to be Pc = 176 ± 4 MPa, Tc = 177 ± 2 K, and ρc = 1.13±0.01 g/cm3. Interestingly, for the water model studied, differences in the LLCP location from PIMD and MD simulations suggest that nuclear quantum effects (i.e., atoms delocalization) play an important role in the thermodynamics of water around the LLCP (from the MD simulations of q-TIP4P/F water, Pc = 203 ± 4 MPa, Tc = 175 ± 2 K, and ρc = 1.03 ± 0.01 g/cm3). Overall, our results strongly support the LLPT scenario to explain water anomalous behavior, independently of the fundamental differences between classical MD and PIMD techniques. The reported values of Tc for D2O and, particularly, H2O suggest that improved water models are needed for the study of supercooled water.

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The Harmonic and Gaussian Approximations in the Potential Energy Landscape Formalism for Quantum Liquids

Zhou,

Lopez,

Giovambattista

2024

J. Chem. Theory Comput.

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The potential energy landscape (PEL) formalism has been used in the past to describe the behavior of classical low-temperature liquids and glasses. Here, we extend the PEL formalism to describe the behavior of liquids and glasses that obey quantum mechanics. In particular, we focus on the (i) harmonic and (ii) Gaussian approximations of the PEL, which have been commonly used to describe classical systems, and show how these approximations can be applied to quantum liquids/glasses. Contrary to the case of classical liquids/glasses, the PEL of quantum liquids is temperature-dependent, and hence, the main expressions resulting from approximations (i) and (ii) depend on the nature (classical vs quantum) of the system. The resulting theoretical expressions from the PEL formalism are compared with results from path-integral Monte Carlo (PIMC) simulations of a monatomic model liquid. In the PIMC simulations, every atom of the quantum liquid is represented by a ring-polymer. Our PIMC simulations show that at the local minima of the PEL (inherent structures, or IS), sampled over a wide range of temperatures and volumes, the ring-polymers are collapsed. This considerably facilitates the description of quantum liquids using the PEL formalism. Specifically, the normal modes of the ring-polymer system/quantum liquid at an IS can be calculated analytically if the normal modes of the classical liquid counterpart are known (as obtained, e.g., from classical MC or molecular dynamics simulations of the corresponding atomic liquid).

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Nuclear quantum effects on the thermodynamic response functions of a polymorphic waterlike monatomic liquid

Cited by 7 publications

References 63 publications

Evidence of a liquid–liquid phase transition in H$$_2$$O and D$$_2$$O from path-integral molecular dynamics simulations

Evidence of a liquid–liquid phase transition in H$$_2$$O and D$$_2$$O from path-integral molecular dynamics simulations

Liquid-Liquid Phase Transition in Supercooled H2O and D2O: A Path-Integral Computer Simulation Study

The Harmonic and Gaussian Approximations in the Potential Energy Landscape Formalism for Quantum Liquids

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