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1.
We study the translocation of a protein-like chain through a finite cylindrical channel using the pruned-enriched Rosenbluth method (PERM) and the modified orientation-dependent monomer-monomer interaction (ODI) model. Attractive channels ( εcp=-2.0, -1.0, -0.5), repulsive channels ( εcp=0.5, 1.0, 2.0), and a neutral channel ( εcp =0) are discussed. The results of the chain dimension and the energy show that Z0=1.0 is an important case to distinguish the types of the channels. For the strong attractive channel, more contacts form during the process of translocation. It is also found that an external force is needed to drive the chain outside of the channel with the strong attraction. While for the neutral, the repulsive, and the weak attractive channels, the translocation is spontaneous. 相似文献
2.
We compare the effect of two body core on the charge form factor of 3He by the hyperspherical harmonics expansion method using various 2BF potentials with the inclusion of three body force. We
also include the meson exchange current contribution to the CFF for the same potentials in addition to the 3BF. The results
indicate that the combined effect of 3BF and MEC (i) moves q
min
2
(the first diffraction minimum) appreciably to the left, amount of shift depends on the 2BF at r
12∼0.7 fm and (ii) enhances F
max (the height of the secondary maximum of CFF) by an appreciable amount, the increment in general increases with the repulsive
core of 2BF ( r⩽0.1 fm). 相似文献
3.
We study the Casimir effect for two parallel slabs immersed in a harmonically trapped Fermi gas. The Casimir force and its
distribution on the slabs are calculated. It is found that the Casimir force oscillates with the separation L
z
of the slabs and can be either attractive or repulsive, depending sensitively on the size of L
z
. It is also found that the size and sign of the Casimir pressure (i.e., the Casimir force on the unit area) oscillates with
the variation of the distance r away from the center of the harmonic potential and its amplitude decreases with the increase of r. 相似文献
4.
The oxygen isotope effect in high- TC superconductors has been investigated on the basis of a two-band model where superconducting phase transition is induced by interband (mainly Coulombic) interaction. The isotope shift of TC appears due to the dependence of averaged interband electronphonon coupling constant on oxygen mass. This coupling has a repulsive nature and gives a relatively small contribution to the total interaction inducing superconductivity. The calculated isotope effect exponent depending on the carrier concentration has been compared with the experimental one as a function of x for La 2-xSr xCuO 4. 相似文献
5.
We elucidate the close connection between the repulsive lattice gas in equilibrium statistical mechanics and the Lovász local lemma in probabilistic combinatorics. We show that the conclusion of the Lovász local lemma holds for dependency graph G and probabilities { px} if and only if the independent-set polynomial for G is nonvanishing in the polydisc of radii { px}. Furthermore, we show that the usual proof of the Lovász local lemma – which provides a sufficient condition for this to occur – corresponds to a simple inductive argument for the nonvanishing of the independent-set polynomial in a polydisc, which was discovered implicitly by Shearer (98) and explicitly by Dobrushin. (37,38) We also present some refinements and extensions of both arguments, including a generalization of the Lovász local lemma that allows for soft dependencies. In addition, we prove some general properties of the partition function of a repulsive lattice gas, most of which are consequences of the alternating-sign property for the Mayer coefficients. We conclude with a brief discussion of the repulsive lattice gas on countably infinite graphs. 相似文献
6.
We present a theoretical investigation of elementary excitations in anisotropic antiferromagnetic S=1 chains using the concept of domain walls in string (hidden) order. Domain walls are classified by the internal spin projection S
dw
z
. We calculate energies and string correlation
0 functions of low lying excited states of the domain wall type in the Haldane phase and compare the results to those of numerical
computations. The boundaries of the Haldane phase are determined from the instability of these excitations with respect to
the ground state. The interaction between two domain walls is found to be proportional to the product S
dw
z
, S
dw
z
2, it is effectively repulsive 0140 for equal
spin projections. 相似文献
7.
Perturbation theory is used to consider expansions for the radial distribution function, g 2( r), of a fluid with a soft core. We consider the Lennard-Jones (12, 6) potential and divide it into repulsive and attractive regions. In the repulsive region we expand the function exp ( β u( r)) g 2( r) about a hard sphere value. For the first-order contribution of the attractive region we consider a simple approximation to the exact analytical expression. The resulting g 2( r) is accurate at densities below about ρσ 3=0·5. 相似文献
8.
We have theoretically investigated the effect of pressure on the structural stability of GaP?:?InP mixed system. The three-body-potential (TBP) model has been used. The TBP model consists of long-range as well as short-range interactions; the long-range part includes the modified Coulomb force as well as a three-body term; the short-range part in TBP defines the van der Waals and overlap repulsive interactions. We observe a pressure-induced structural phase transformation from ZnS (B3) to NaCl (B1) type phase in Ga 1?x In x P. Our calculated transition pressures for the initial GaP and final InP compound semiconductors are in good agreement with other reported data. 相似文献
9.
Microalloying experiments on amorphous Al 84La 4Er 2Ni 8TM 2 alloys were performed with the substitution of all 3 d TM (transition metal) elements and one 4 d TM element. The critical thickness of the amorphous alloys was used as a criterion for glass formability in this system. The results show that, other than atomic size differences and the negative heats of mixing among the solvent and solute atoms, the atomic interactions among the solute atoms play an important role on glass formation. When the solute–solute interaction becomes repulsive (positive heat of mixing), glass formability suffers. Similarly, when the solute–solute interaction becomes highly attractive, exceeding that between the solvent and solute atoms, glass formability is also degraded. Evaluation of a large number of known multicomponent bulk metallic glasses provides additional support to these conjectures. This study shows that the solute–solute interaction plays an important role in glass formation, which has not been recognized previously. 相似文献
10.
We use different determinantal Hartree-Fock (HF) wave functions to calculate true variational upper bounds for the ground
state energy of N spin-half fermions in volume V
0, with mass m, electric charge zero, and magnetic moment μ, interacting through magnetic dipole-dipole interaction. We find that at high
densities when the average interparticle distance r
0 becomes small compared to the magnetic length r
m ≡ 2 mμ 2/ħ 2, a ferromagnetic state with spheroidal occupation function n
↑(), involving quadrupolar deformation, gives a lower upper bound compared to the variational energy for the uniform paramagnetic
state or for the state with dipolar deformation. This system is unstable towards infinite density collapse, but we show explicitly
that a suitable short-range repulsive (hard core) interaction of strength U
0 and range a can stop this collapse. The existence of a stable equilibrium high density ferromagnetic state with spheroidal occupation
function is possible as long as the ratio of coupling constants Γ cm ≡ ( U
0
a
3/μ 2) is not very small compared to 1.
相似文献
11.
The adiabatic theorem, an important theory in quantum mechanics, tells that a quantum system subjected to gradually changing external conditions remains to the same instantaneous eigenstate of its Hamiltonian as it initially in. In this paper, we study the quench evolution that is another extreme circumstance where the external conditions vary rapidly such that the quantum system can not follow the change and remains in its initial state (or wavefunction). We examine the matter-wave pressure and derive the requirement for such an evolution. The study is conducted by considering a quantum particle in an infinitely deep potential, the potential width Q is assumed to be change rapidly. We show that the total energy of the quantum subsystem decreases as Q increases, and this rapidly change exerts a force on the wall which plays the role of boundary of the potential. For Q < Q0 (Q0 is the initial width of the potential), the force is repulsive, and for Q > Q0, the force is positive. The condition for the quenching evolution evolution is given via a spin-\( \frac{1}{2} \) in a rotating magnetic field. 相似文献
12.
The Casimir effect for two parallel slabs immersed in an ideal Fermi sea is investigated at both zero and nonzero temperatures. It is found that the Casimir effect in a Fermi gas is distinctly different from that in an electromagnetic field or a massive Bose gas. In contrast to the familiar result that the Casimir force decreases monotonically with the increase of the separation L between two slabs in an electromagnetic field and a massive Bose gas, the Casimir force in a Fermi gas oscillates as a function of L. The Casimir force can be either attractive or repulsive, depending sensitively on the magnitude of L. In addition, it is found that the amplitude of the Casimir force in a Fermi gas decreases with the increase of the temperature, which also is contrary to the case in a Bose gas, since the bosonic Casimir force increases linearly with the increase of the temperature in the region T < Tc, where Tc is the critical temperature of the Bose-Einstein condensation. 相似文献
13.
Nano TiO 2 was dispersed in ethylene glycol (EG) by the replacement of dispersion medium from water sol. EG/TiO 2 suspension was well stabilized by the electrostatic repulsive force when pH value of suspension was less than 4.3. In situ polymerization starting from bis(2-hydroxyethyl) terephthalate (BHET) and EG/TiO 2 suspension was carried out to prepare a series of poly(ethylene terephthalate) (PET)/TiO 2 nanocomposites. Under highly acidic conditions, 97% particles dispersed in PET matrix had the size less than 100 nm. With the increase of pH value, aggregation occurred and larger size particles appeared. A tensile test showed that Young's modulus of PET was increased by the addition of nano TiO 2 相似文献
14.
YBaCuO (YBCO) bulk materials with large superconductive domains were fab-ricated using a small SmBa 2Cu 3O x grain as the seed for growth, The capacities of strong flux pinning and well grain linking in the material have been shown in the investigations on magnetization loop end ac susceptibility. The strong flux pinning made it possible for the large YBCO bulk to capture a great dea. l of flux and keep the residual magnetism stable. The residual field intensity H rem was shown to have a maximum of 0.125 T after the 0.5 T NdFeB magnetizing field was moved away. We did not find much decline of H rem in a short time. The magnetized YBCO bulk pro-duced repulsive force upon another YBCO bulk as the permanent magnet did. We measured and calculated the force between two YBCO bulks. The theoretical result was in agreement with the experimental one by and large. 相似文献
15.
The Casimir effect is highly dependent on the shape and structure of space boundaries. This dependence is encoded in the variation
of vacuum energy with the different types of boundary conditions. We analyze from a global perspective the properties of the
Casimir energy as a function on the largest space of the consistent boundary conditions MF\mathcal{M}_{F} for a massless scalar field confined between to homogeneous parallel plates. In particular, we analyze the analytic properties
of this function and point out the existence of a third order phase transition at periodic boundary conditions. We also characterize
the boundary conditions which give rise to attractive or repulsive Casimir forces. In the interface between both regimes we
find a very interesting family of boundary conditions without Casimir effect, and fully characterize the boundary conditions
which do not induce any type of Casimir force. 相似文献
16.
A model for N-N interaction proposed earlier by two of us (VSB and VKG), has been extended to incorporate the tensor component of the nuclear
force. Based on the quark compound bag model (QCB), the nucleon-nucleon potential has a short range repulsive core which is
non-local and has a characteristic energy dependence and is expressed in terms of the parameters relating to the six-quark
compound bag. To account for the low energy properties, this repulsive core interaction is supplemented by a phenomenological
non-local potential containing both central ( S-wave) and tensor components and operates only outside the QCB. Using this model, we analyse and compare the results with
the experimental data for the electromagnetic form factors of the deuteron, the D-state observables, such as the quadrupole moment, the D-state probability, and the D/S ratio along with the n-p scattering phase shifts up to about 400 MeV. 相似文献
17.
The purpose of this paper is to investigate the interplay between the chemical shielding anisotropy and quadrupole interaction in MQMAS spectra.
in the compounds Na 3Co(NO 2) 6 and trans-Co[(en 2)(NO 2) 2]NO 3 provides model systems for such an investigation. Furthermore, only few results have been reported on the application of the MQMAS method to a spin I=7/2. The possibilities of the MQMAS spectroscopy for determining the relative orientation of the two tensors and its advantage over previous techniques are discussed. Reported experimental spectra at different spinning speeds of Na 3Co(NO 2) 6 are accurately reproduced by our theoretical simulations. The calculations are based on a recent approach, summarized in the present paper, which allows one to perform efficient simulations of MQMAS spectra including all interactions and their time-dependence throughout the experiment. This is necessary for calculating accurate MQMAS spectra including the spinning sideband pattern. In the case of trans-Co[(en 2)(NO 2) 2]NO 3 where the quadrupolar interaction and chemical shielding are stronger and their axes are non-coincident, the MQMAS spectrum is strongly distorted due to the unsufficient spinning speed and RF power. In this case, MAS at different spinning speeds is shown to provide valuable information. 相似文献
18.
Potential energy curves(PECs) for the ground state(X 2 Σ +) and the four excited electronic states(A 2 Π,B 2 Π,C 2 Σ +,4 Π) of a BeH molecule are calculated using the multi-configuration reference single and double excited configuration interaction(MRCI) approach in combination with the aug-cc-pVTZ basis sets.The calculation covers the internuclear distance ranging from 0.07 nm to 0.70 nm,and the equilibrium bond length R e and the vertical excited energy T e are determined directly.It is evident that the X2Σ+,A2Π,B2Π,C2Σ+ states are bound and 4Π is a repulsive excited state.With the potentials,all of the vibrational levels and inertial rotation constants are predicted when the rotational quantum number J is set to be equal to zero(J = 0) by numerically solving the radial Schr¨odinger equation of nuclear motion.Then the spectroscopic data are obtained including the rotation coupling constant ω e,the anharmonic constant ωexe,the equilibrium rotation constant Be,and the vibration-rotation coupling constant αe.These values are compared with the theoretical and experimental results currently available,showing that they are in agreement with each other. 相似文献
19.
An algebraic model to describe inelastic collisions between two anharmonic diatomic molecules in the semiclassical approximation is presented. The interactions for the diatomic systems are modelled in terms of Morse potentials, while an exponential repulsive potential is taken for the interactions between the nearest atoms of the diatomic systems. This problem is treated in the interaction potential framework, where an approximation in terms of the generators of three SU(2) groups is proposed, two corresponding to the Morse oscillators and the other to the interaction. The transition probabilities are given in terms of a sum of the products of three Wigner's d(β) functions corresponding to the three SU(2) groups. As an example the systems N 2?+?N 2 and H 2?+?H 2 are described and compared with exact quantum mechanical calculations. 相似文献
20.
为了产生大尺度氘团簇用于与强激光相互作用研究,研制了低温高背压团簇源.利用瑞利散射法对团簇尺度与气体背压相关性和团簇的形成演变过程进行了研究.得到团簇尺度 Nc随背压的指数变化关系为 Nc∝ P2.890,当气体温度为80K,背压 P0为48×10 5Pa时,氘团簇尺度 Nc≈2630,并得到了团
关键词:
氘团簇
团簇源
瑞利散射
激光与团簇相互作用 相似文献
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