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On the triplet of holographic phase transition

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arXiv 2021年

作者： Phat, Tran Huu Nguyen, Toan T. Vietnam Atomic Energy Commission 59 Ly Thuong Kiet street Hoan Kiem Hanoi100000 Viet Nam Key Laboratory for Multiscale Simulation of Complex Systems Department of Theoretical Physics University of Science Vietnam National University − Hanoi 334 Nguyen Trai street Thanh Xuan Hanoi100000 Viet Nam

We start from an Einstein − Maxwell system coupled with a charged scalar field in Anti−de Sitter space−time. In the setup where the pressure P is identified with the cosmological constant, the AdS black hole (BH) undergoes the phase transition from small to large BHs, which is similar to the transition from liquid to gas in the van der Waals theory. Based on this framework, we study the triplet of holographic superconducting states, consisting of ground state and two lowest excited states. Our numerical calculations show that the pressure variation in the bulk creates a mechanism in the boundary which causes changes in the physical properties of excited states, namely: a) when the pressure P is higher than the critical pressure Pc (P > Pc) of the phase transition from small to large BHs the ground state and the first excited state are superconducting states while the second excited state is the normal one. However, at lower pressure, P ≤ Pc, the ground state is solely the superconducting state. We conjecture that the precedent phenomena could take place when the scalar field in the bulk is replaced by other matter fields. Copyright © 2021, The Authors. All rights reserved.

关键词： Ground state

Asymptotic critical behavior of holographic phase transition at finite topological charge - the spectrum of excited states becomes continuous at T = 0

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arXiv 2021年

作者： Nguyen, Toan T. Phat, Tran Huu Key Laboratory for Multiscale Simulation of Complex Systems Department of Theoretical Physics University of Science Vietnam National University – Hanoi 334 Nguyen Trai street Thanh Xuan Hanoi100000 Viet Nam Vietnam Atomic Energy Commission 59 Ly Thuong Kiet street Hoan Kiem Hanoi100000 Viet Nam

Within the framework of AdS/CFT duality, excited states of the conformal field living at the global AdS boundary of a four-dimensional spacetime Einstein gravity are investigated analytically in the probe limit where the field equations are linearized. At asymptotically large values, the threshold chemical potential for the appearance of excited condensate states are discrete, equal spacing, with the gap approaches zero logarithmically in the limit T → 0. Remarkably, numerical results show that, this behavior applies even for states as low as for the first or the second excited state of the condensate. This is especially significant on the liquid side of the black hole van der Waals - like phase transition (small or zero topological charge) where there seems to be no gap between the ground state and the first excited state at zero temperature. We postulate that, at the exact limit T = 0 where the gap is zero, the spectrum of threshold chemical potentials becomes continuous, all excited states of the condensate are activated above a finite chemical potential, suggesting a new quantum phase transition as a function of the chemical potential. Previous studies have largely missed this continuous spectrum of excited states in the T → 0 limit. This fact should be taken into account carefully in AdS/CFT duality studies. Copyright © 2021, The Authors. All rights reserved.

关键词： Excited states

Influence of fatty alcohol mixing ratios on the physicochemical properties of stearyl-cetyl alcohol-polysorbate 60-water ternary system: Insights from experiments and computer simulations

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arXiv 2021年

作者： Hoang, Vu Dang Cong, Cao Phuong Tran, Hung Huu Nguyen, Hue Minh Thi Nguyen, Toan T. Department of Analytical Chemistry and Toxicology Hanoi University of Pharmacy 13-15 Le Thanh Tong street Hanoi Viet Nam Key Laboratory for Multiscale Simulation of Complex Systems VNU University of Science Vietnam National University 334 Nguyen Trai street Thanh Xuan Hanoi120401 Viet Nam Faculty of Chemistry and Center for Computational Science Hanoi National University of Education 136 Xuan Thuy street Cau Giay Hanoi Viet Nam

The structure and stability of ternary systems prepared with polysorbate 60 and various combinations of cetyl (C16) and stearyl (C18) alcohols were examined as they aged over 3 months at 25◦C. Rheological results showed that the consistency of these systems increased initially during roughly the first week of aging, which was succeeded by little changes in consistency (systems containing from 30% to 70% C18, with the 50% C18 system showing the highest consistencies) or significant breakdown of structure (remaining systems). The formation and/or disintegration of all ternary systems were also detected by microscopy and differential scanning calorimetry experiments. This study emphasizes the fact that the structure and consistency of ternary systems are dominantly controlled by the swelling capacity of the lamellar gel phase. Molecular dynamics simulations were performed to provide details on the molecular mechanism of stability. Computational results support the hypothesis experimentally proposed for the stability of the mixed system being due to an increase flexibility of the alcohol with a longer hydrocarbon chain. Computational results are in excellent agreement with experimental conclusions. Additionally, they show that in the mixed system, alcohols with shorter hydrocarbon chain become more rigid. These molecular details could not be available in experimental measurements. Copyright © 2021, The Authors. All rights reserved.

关键词： Molecular dynamics

Computational study of µ-opioid receptor embedded in a realistic membrane

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Journal of Physics: Conference Series 2020年第1期1506卷

作者： Thanh K. Tran Toan T. Nguyen Key Laboratory for Multiscale of Complex Systems VNU University of Science Vietnam National University 334 Nguyen Trai street Thanh Xuan district Hanoi 120000 VIETNAM

Opioids are highly effective analgesics used to alleviate acute, surgical and cancer pains. However, utilization of opioids leads to adverse effects such as nausea, constipation, dizziness, somnolence, vomiting, especially, high addictive liability and drug-induced respiration depression. Ongoing efforts to generate safer opioid analgesics, such as designing biased agonist, peripheral opioids or endogenous opioid analogues, requires thorough understanding of the relationship between structure and function of the main target of opioids - µORs. In this research, the structural and dynamic of a µOR molecule embedded in membrane are studied by molecular dynamics simulation. Our results revealed the influences of disulfide linkage between CYS142-CYS219 and the transmembrane proline and glycine on µOR's dynamics and structure, as well as, their important role in µOR's functions.

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Effects of surface charge and environmental factors on the electrostatic interaction of fiber with virus-like particle: A case of coronavirus

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arXiv 2021年

作者： Dung, Dinh Ngoc Phan, Anh D. Nguyen, Toan T. Lam, Vu D. Faculty of Materials Science and Engineering Phenikaa University Yen Nghia Ha Dong Ha Noi12116 Viet Nam Phenikaa Institute for Advanced Study Phenikaa University Yen Nghia Ha Dong Ha Noi12116 Viet Nam Key Laboratory for Multiscale Simulation of Complex Systems Faculty of Physics VNU University of Science Vietnam National University – Hanoi 334 Nguyen Trai Street Thanh Xuan District Hanoi10000 Viet Nam Graduate University of Science and Technology Vietnam Academy of Science and Technology 18 Hoang Quoc Viet Hanoi Viet Nam

We propose a theoretical model to elucidate intermolecular electrostatic interactions between a virus and a substrate. Our model treats the virus as a homogeneous particle having surface charge and the polymer fiber of the respirator as a charged plane. Electric potentials surrounding the virus and fiber are influenced by the surface charge distribution of the virus. We use Poisson-Boltzmann equations to calculate electric potentials. Then, Derjaguin’s approximation and a linear superposition of the potential function are extended to determine the electrostatic force. In this work, we apply this model for coronavirus or SARS-CoV-2 case and numerical results quantitatively agree with prior simulation. We find that the influence of fiber’s potential on the surface charge of the virus is important and is considered in interaction calculations to obtain better accuracy. The electrostatic interaction significantly decays with increasing separation distance, and this curve becomes steeper when adding more salt. Although the interaction force increases with heating, one can observe the repulsive-attractive transition when the environment is acidic. Copyright © 2021, The Authors. All rights reserved.

关键词： Boltzmann equation

Charged AdS black hole and the quantum tunneling from black hole to white hole

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arXiv 2022年

作者： Phat, T.H. Anh, N.T. Nguyen, Toan T. Quyet, H.V. Vietnam Atomic Energy Commission 59 Ly Thuong Kiet Hanoi Viet Nam Faculty of Energy Technology Electric Power University 235 Hoang Quoc Viet Hanoi Viet Nam Key Laboratory for Multiscale Simulation of Complex Systems Department of Theoretical Physics University of Science Vietnam National University − Hanoi 334 Nguyen Trai street Thanh Xuan Hanoi100000 Viet Nam Department of Physics Hanoi Pedagogical University 2 Vinh Phuc Phuc Yen15000 Viet Nam

In this paper, we show that depending on the sign of the electric charge Q, the charged AdS black hole (BH) possesses two alternative facets when the cosmological constant is identified to the thermodynamic pressure P. It is discovered that: 1) the equation of state of BH corresponds to Q > 0 and when Q changes from Q > 0 to Q WH (T) which releases in this process equals with minus sign the latent heat of BH, too;3) Finally, the probability of the quantum tunneling from the BH to the WH is obtained. We suggest the perspective of application of the results above to the AdS/CFT duality. Copyright © 2022, The Authors. All rights reserved.

关键词： Gravitation

Grand−canonical Monte−Carlo simulation of DNA condensation in equilibrium with a salt mixture containing 2:2 salt

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Journal of Physics: Conference Series 2017年第1期865卷

作者： Nguyen V Duc Toan T Nguyen Faculty of Physics VNU University of Science Vietnam National University 334 Nguyen Trai Street Thanh Xuan Hanoi Vietnam VNU Key Laboratory for Multiscale Simulation of Complex Systems Vietnam National University 334 Nguyen Trai Street Thanh Xuan Hanoi Vietnam School of Physics Georgia Institute of Technology 837 State Street Atlanta Georgia 30332-0430 USA

The Grand–canonical Monte–Carlo simulation method is used to simulate DNA hexagonal condensate in the presence of a mixture of 1:1, 2:1, 2:2 salts using the primitive ion model. Previous results show that DNA can be condensed by divalent counterions in restricted environment, such as inside viruses. In this work, we study the effects of divalent co-ions on condensation of DNA by divalent counterions. It is shown that divalent co–ions lead to weaker DNA condensation free energy and DNA de–condensation at smaller counterions concentration.

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Impact of Ligand Fields on Kubas Interaction of Open Copper Sites in Mofs with Hydrogen Molecules: An Electronic Structural Insight

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SSRN

SSRN 2024年

作者： Nguyen-Thuy, Trang Tran-Van, Hoan Nguyen-Hoang, Linh Nguyen-Minh, Hoang Phan, Bach Thang Nguyen-The, Toan Kawazoe, Yoshiyuki Faculty of physics University of Science Vietnam National University – Hanoi Hanoi Viet Nam School of engineering physics Hanoi University of Technology Hanoi Viet Nam Center for Innovative Materials and Architectures Vietnam National University Ho Chi Minh City Ho Chi Minh City Viet Nam Vietnam National University HoChiMinh City Viet Nam Key Laboratory for Multiscale Simulation of Complex Systems University of Science Vietnam National University – Hanoi Hanoi Viet Nam New Industry Creation Hatchery Center Tohoku University Sendai980-8579 Japan Department of Physics and Nanotechnology SRM Institute of Science and Technology Tamil Nadu Kattankulathur603203 India School of Physics Institute of Science Suranaree University of Technology 111 University Avenue Nakhon Ratchasima30000 Thailand

Using DFT calculations, we investigate hydrogen sorption on open copper sites in various ligand coordinations of metal-organic frameworks (MOFs), including the triangle coordination T(CuL3) in MFU-4l, the linear coordination L(CuL2) in NU2100 and the paddlewheel coordination P(CuL4)2 in HKUST-1. By examining the ligand field splitting of d states and spd hybridizations in copper, we reveal the electronic mechanisms influencing hydrogen sorption performance. Despite Cu+ oxidization state which is expected to facilitate strong Kubas interaction with hydrogen molecules, the vacant s-p-dz2 hybrid orbitals of the open copper site in the L(CuL2) coordination are unsuitable for overlapping with the H2 s bonding orbital, preventing hydrogen adsorption. In contrast, the T(CuL3) and P(CuL4)2 coordinations enable hydrogen adsorption by inducing suitable hydrid orbitals. The vacant Cu s-p-dz2 hybrid orbitals in these cases can overlap with the H2 s bonding orbital to facilitate electron forward donation, forming bonding states between the Cu s-p-dz2 and H2 s bonding orbitals. The occupied Cu s-p-dxz/yz and s-p-dx2-y2 hybrid orbitals in the case of T(CuL3) promote the electron back donation to the H2 s* antibonding orbital, leading to the formation of bonding states. Conversely, in P(CuL4)2 coordination, the absence of such hybridization results in the lack of electron back donation. The complete Kubas interaction with both forward and back electron donations is responsible for a higher adsorption energy of 37.6 kJ/mol in the case of T(CuL3) than the value of 10.6 kJ/mol in the P(CuL4)2 coordination. © 2024, The Authors. All rights reserved.

关键词： Electronic structure

Correction: Impact of ligand fields on Kubas interaction of open copper sites in MOFs with hydrogen molecules: an electronic structural insight

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RSC advances 2024年第44期14卷 32471页

作者： Trang Thuy Nguyen Hoan Van Tran Linh Hoang Nguyen Hoang Minh Nguyen Thang Bach Phan Toan Nguyen-The Yoshiyuki Kawazoe Faculty of Physics University of Science Vietnam National University Hanoi Vietnam nguyenthuytrang@hus.edu.vn. Key Laboratory for Multiscale Simulation of Complex Systems University of Science Vietnam National University Hanoi Vietnam. School of Engineering Physics Hanoi University of Science and Technology Hanoi Vietnam. Center for Innovative Materials and Architectures Vietnam National University Ho Chi Minh City Vietnam. Vietnam National University Ho Chi Minh City Vietnam. New Industry Creation Hatchery Center Tohoku University Sendai 980-8579 Japan. Department of Physics and Nanotechnology SRM Institute of Science and Technology Kattankulathur 603203 Tamilnadu India. School of Physics Institute of Science Suranaree University of Technology 111 University Avenue Nakhon Ratchasima 30000 Thailand.

[This corrects the article DOI: 10.1039/D4RA03946G.].

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