In this study, we use the density functional theory (DFT) calculations and the molecular dynamics (MD) simulations to investigate the performance of graphenylene-1 membrane for hydrogen (H 2 ) purification and helium (He) separation. The stability of this membrane is confirmed by calculating its cohesive energy. Our results show that a surmountable energy barrier for H 2 (0.384 eV) and He (0.178 eV) molecules passing through graphenylene-1 membrane. At room temperature, the selectivity of H 2 /CO 2 , H 2 /N 2 , H 2 /CO and H 2 /CH 4 are obtained as 3 × 10 27 , 2 × 10 18 , 1 × 10 17 and 6 × 10 46 , respectively. Furthermore, we demonstrate that graphenylene-1 membrane exhibits the permeance of H 2 and He molecules are much higher than the value of them in the current industrial applications specially at temperatures above 300 K and 150 K, respectively. We further performed MD simulations to confirm the results of DFT calculations. All these results show that graphenylene-1 monolayer membrane is an excellent candidate for H 2 purification and He separation. arXiv:1909.02112v2 [cond-mat.mtrl-sci]

In this study, we solve analytically the Schrödinger equation for a macroscopic quantum oscillator as a central system coupled to two environmental micro-oscillating particles. Then, the double-slit interference patterns are investigated in two limiting cases, considering the limits of uncertainty in the position probability distribution. Moreover, we analyze the interference patterns based on a recent proposal called stochastic electrodynamics with spin. Our results show that when the quantum character of the macro-system is decreased, the diffraction pattern becomes more similar to a classical one. We also show that, depending on the size of the slits, the predictions of quantum approach could be apparently different with those of the aforementioned stochastic description.

We propose an experiment to investigate the possibility of long-distance thermodynamic relationships between two entangled particles. We consider a pair of spin-$$\frac{1}{2}$$ 1 2 particles prepared in an entangled singlet state in which one particle is sent to Alice and the other to her distant mate Bob, who are spatially separated. Our proposed experiment consists of three different setups: First, both particles are coupled to two heat baths with various temperatures. In the second setup, only Alice’s particle is coupled to a heat bath and finally, in the last setup, only Bob’s particle is coupled to a heat bath. We study the evolution of an open quantum system using the first law of thermodynamics based on the concepts of ergotropy, adiabatic work, and operational heat, in a quantum fashion. We analyze and compare ergotropy and heat transfer in three setups. Our results show that the heat transfer for each entangled particle is not independent of the thermalization process that occurs for the other one. We prove that the existence of quantum correlations affects the thermodynamic behavior of distant particles in an entangled state.

In order to separate a mixture of hydrogen ($$\text {H}_{2}$$ H 2 ) and carbon dioxide ($$\text {CO}_{2}$$ CO 2 ) gases, we have proposed a new approach employing the graphdiyne-like membrane (GDY-H) using density functional theory (DFT) calculations and molecular dynamics (MD) simulations. GDY-H is constructed by removing one-third diacetylenic ($${{-}\text {C}{\equiv}\text {C}{-}\text {C}{\equiv}\text {C}{-}}$$ - C ≡ C - C ≡ C - ) bonds linkages and replacing with hydrogen atoms in graphdiyne structure. Our DFT calculations exhibit poor selectivity and good permeances for $$\text {H}_{2}$$ H 2 /$$\text {CO}_{2}$$ CO 2 gases passing through this membrane. To improve the performance of the GDY-H membrane for $$\text {H}_{2}$$ H 2 /$$\text {CO}_{2}$$ CO 2 separation, we have placed two layers of GDY-H adjacent to each other which the distance between them is 2 nm. Then, we have inserted 1,3,5-triaminobenzene between two layers. In this approach, the selectivity of $$\text {H}_{2}$$ H 2 /$$\text {CO}_{2}$$ CO 2 is increased from 5.65 to completely purified $$\text {H}_{2}$$ H 2 gas at 300 K. Furthermore, GDY-H membrane represents excellent permeance, about $$10^8$$ 10 8 gas permeation unit (GPU), for $$\text {H}_{2}$$ H 2 molecule at temperatures above 20 K. The $$\text {H}_{2}$$ H 2 permeance is much higher than the value of the usual industrial limits. Moreover, our proposed approach shows a good balance between the selectivity and permeance parameters for the gas separation which is an essential factor for $$\text {H}_{2}$$ H 2 purification and $$\text {CO}_{2}$$ CO 2 capture processes in the industry.

The macroscopic quantum systems are considered as a bridge between quantum and classical systems. In this study, we explore the validity of the original Heisenberg position-momentum uncertainty relation for a macroscopic harmonic oscillator interacting with environmental micro-particles. Our results show that, in the quasi-classical situation, the original uncertainty relation does not hold, when the number of particles in the environment is small. Nonetheless, increasing the environmental degrees of freedom removes the violation bounds in the regions of our investigation.