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1.
Investigations on spectroscopic parameters, vibrational levels, classical turning points and inertial rotation and centrifugal distortion constants for the X1∑+g state of sodium dimer 下载免费PDF全文
The density functional theory (B3LYP, B3P86) and the quadratic
configuration-interaction method including single and double
substitutions (QCISD(T), QCISD) presented in Gaussian03 program
package are employed to calculate the equilibrium internuclear
distance $R_{\rm e}$, the dissociation energy $D_{\rm e }$ and the
harmonic frequency $\omega _{\rm e}$ for the $X{}^{1}\Sigma^{ +
}_{\rm g}$ state of sodium dimer in a number of basis sets. The
conclusion is gained that the best $R_{\rm e}$, $D_{\rm e}$ and
$\omega _{\rm e}$ results can be attained at the
QCISD/6-311G(3df,3pd) level of theory. The potential energy curve at
this level of theory for this state is obtained over a wide
internuclear separation range from 0.16 to 2.0~nm and is fitted to
the analytic Murrell--Sorbie function. The spectroscopic parameters
$D_{\rm e}$, $D_{0}$, $R_{\rm e}$, $\omega _{\rm e}$,
$\omega _{\rm e}\chi _{\rm e}$,
$\alpha _{\rm e}$
and $B_{\rm e}$ are calculated to be 0.7219~eV,
0.7135~eV, 0.31813~nm, 151.63~cm$^{ - 1}$, 0.7288~cm$^{ - 1}$,
0.000729~cm$^{ - 1}$ and 0.1449~cm$^{ - 1}$, respectively, which are in good
agreement with the measurements. With the potential obtained at the
QCISD/6-311G(3df,3pd) level of theory, a total of 63 vibrational
states is found when $J=0$ by solving the radial Schr\"{o}dinger equation
of nuclear motion. The vibrational level, corresponding classical turning
point and inertial rotation constant are computed for each vibrational
state. The centrifugal distortion constants
($D_{\upsilon }\, H_{\upsilon }$,
$L_{\upsilon }$, $M_{\upsilon }$, $N_{\upsilon }$ and $O_{\upsilon })$ are
reported for the first time for the first 31 vibrational states when $J=0$. 相似文献
2.
The analytical transfer matrix method (ATMM) is applied to
calculating the critical radius $r_{\rm c}$ and the dipole
polarizability $\alpha_{\rm d}$ in two confined systems: the hydrogen
atom and the Hulth\'{e}n potential. We find that there exists a
linear relation between $r_{\rm c}^{1/2}$ and the quantum number $n_{r}$
for a fixed angular quantum number $l$, moreover, the three bounds
of $\alpha_{\rm d}$ ($\alpha_{\rm d}^{K}$, $\alpha_{\rm d}^{B}$,
$\alpha_{\rm d}^{U}$) satisfy an inequality:
$\alpha_{\rm d}^{K}\leq\alpha_{\rm d}^{B}\leq\alpha_{\rm d}^{U}$. A comparison
between the ATMM, the exact numerical analysis, and the variational
wavefunctions shows that our method works very well in the systems. 相似文献
3.
The splitting of potential energy curves for the states
$X^{2}\Pi _{3/2}$, $^{2}\Pi _{1/2}$ and $A^{2}\Sigma ^{ +}$ of
hydroxyl OH under spin--orbit coupling (SOC) has been calculated by
using the SO multi-configuration quasi-degenerate perturbation theory
(SO-MCQDPT). Their Murrell--Sorbie (M--S) potential functions have been
derived, then, the spectroscopic constants for $X^{2}\Pi _{3/2}$,$^{
2}\Pi _{1/2}$ and $A^{2}\Sigma ^{ + }$ have been derived from the
M--S function. The calculated dissociation energies for the three states are
$D_{0}$[OH($X^{2}\Pi _{3/2})$]=34966.632cm$^{-1}$,
$D_{0}$[OH($^{2}\Pi _{1/2})$]=34922.802cm$^{-1}$, and
$D_{0}$[OH($A^{2}\Sigma ^{ + })$]=17469.794cm$^{-1}$, respectively. The
vertical excitation energy $\nu [ {{ }^2\Pi _{1/2} ( {\nu = 0}
) \to {X}{ }^2\Pi _{3/2} ( {\nu = 0} )} ] =
139.6{\rm cm}^{-{\rm 1}}$. All the spectroscopic data for the
$X^{2}\Pi _{3/2}$ and $^{2}\Pi _{1/2 }$ are given for the
first time except the dissociation energy of $X^{2}\Pi _{3/2}$. 相似文献
4.
Multireference configuration interaction potential curve and analytical potential energy function of the ground and low-lying excited states of CdSe 下载免费PDF全文
The potential energy curves (PECs) of the ground state ($^{3}\Pi )$
and three low-lying excited states ($^{1}\Sigma $, $^{3}\Sigma $,$^{
1}\Pi )$ of CdSe dimer have been studied by employing
quasirelativistic effective core potentials on the basis of the
complete active space self-consistent field method followed by
multireference configuration interaction calculation. The four PECs
are fitted to analytical potential energy functions using the
Murrel--Sorbie potential function. Based on the PECs, the vibrational
levels of the four states are determined by solving the
Schr\"{o}dinger equation of nuclear motion, and corresponding
spectroscopic constants are accurately calculated. The equilibrium
positions as well as the spectroscopic constants and the vibrational
levels are reported. By our analysis, the $^{3}\Pi $ state, of which
the dissociation asymptote is Cd($^{1}$S) + Se($^{3}$P), is
identified as a ground state of CdSe dimer, and the corresponding
dissociation energy is estimated to be 0.39\,eV. However, the first
excited state is only 1132.49\,cm$^{ - 1}$ above the ground state and
the $^{3}\Sigma $ state is the highest in the four calculated states. 相似文献
5.
New two-fold integration transformation for the Wigner operator in phase space quantum mechanics and its relation to operator ordering 下载免费PDF全文
Using the Weyl ordering of operators expansion formula (Hong-Yi
Fan, \emph{ J. Phys.} A {\bf 25} (1992) 3443) this paper finds a
kind of two-fold integration transformation about the Wigner
operator $\varDelta \left( q',p'\right) $
($\mathrm{q}$-number transform) in phase space quantum mechanics,
$\iint_{-\infty}^{\infty}\frac{{\rm d}p'{\rm d}q'}{\pi
}\varDelta \left( q',p'\right) \e^{-2\i\left(
p-p'\right) \left( q-q'\right) }=\delta \left(
p-P\right) \delta \left( q-Q\right),$
and its inverse%
$
\iint_{-\infty}^{\infty}{\rm d}q{\rm d}p\delta \left( p-P\right)
\delta \left( q-Q\right) \e^{2\i\left( p-p'\right) \left(
q-q'\right) }=\varDelta \left(
q',p'\right),$ where $Q,$ $P$ are the coordinate
and momentum operators, respectively. We apply it to study mutual
converting formulae among $Q$--$P$ ordering, $P$--$Q$ ordering and Weyl
ordering of operators. In this way, the contents of phase space
quantum mechanics can be enriched. The formula of the Weyl
ordering of operators expansion and the technique of integration within the Weyl
ordered product of operators are used in this discussion. 相似文献
6.
In this paper the generation of four-wave mixing (FWM) signal using a
noncycling transition of caesium atoms is investigated when the pumping laser
is locked to the transition $6{\rm S}_{1/2}F=4\to6{\rm P}_{3/2}F'=4$, and
meanwhile the probe frequency is scanned across the $6{\rm S}_{1/2}F=4
\to6{\rm P}_{3/2}$ transition. The efficiency of the four-wave mixing signal
as a function of the intensity of the pumping beams and the detuning of the
pumping beams is also studied. In order to increase the detection
efficiency, a repumping laser which is resonant with $6{\rm S}_{1/2}
F=3\to 6{\rm P}_{3/2}F'=4$ transition is used. A theoretical model is also
introduced, and the theoretical results are in qualitative agreement with
experimental ones. 相似文献
7.
Based on the MIS model, a simple method to extract parameters of
SiC Schottky diodes is presented using the $I$-$V$ characteristics.
The interface oxide capacitance $C_\i$ is extracted for the first time,
as far as we know. Parameters of 4H-SiC Schottky diodes fabricated
for testing in this paper are: the ideality factor $n$, the series
resistance $R_{\rm s}$, the zero-field barrier height $\phi_{\rm B0}$,
the interface state density $D_{\rm it}$, the interface oxide
capacitance $C_\i$ and the neutral level
of interface states $\phi_0$. 相似文献
8.
The transfer of the quantum correlation from two-mode nonclassical state field to the supercurrents in two distant SQUID rings 下载免费PDF全文
We have considered two distant mesoscopic superconducting quantum
interference device (SQUID) rings A and B in the presence of two-mode
nonclassical state fields and investigated the correlation of the
supercurrents in the two rings using the normalized correlation
function $C_{\rm AB}$. We show that when the parameter $\alpha$ is
very small for the separable state with the density matrix $\hat
{\rho } = (\left| {\alpha , - \alpha } \right\rangle \left\langle
{\alpha , - \alpha } \right| + \left| { - \alpha ,\alpha }
\right\rangle \left\langle { - \alpha ,\alpha } \right|) / 2$ and
entangled coherent state (ECS) $\left| u \right\rangle = N_1 (\left|
{\alpha , - \alpha } \right\rangle + \left| { - \alpha ,\alpha }
\right\rangle )$ fields, the dynamic behaviours of the normalized
correlation function $C_{\rm AB}$ are similar, but it is quite
different for the entangled coherent state $\left| {u}'
\right\rangle = N_2 (\left| {\alpha , - \alpha } \right\rangle -
\left| { - \alpha ,\alpha } \right\rangle )$ field. When the
parameter $\alpha $ is very large, the dynamic behaviours of $C_{\rm
AB}$ are almost the same for the separable state, entangled coherent
state $\left| u \right\rangle $ and $\left| {u}' \right\rangle $
fields. For the two-mode squeezed vacuum state field the maximum of
$C_{\rm AB}$ increases monotonically with the squeezing parameter
$r$, and as $r \to \infty $, $C_{\rm AB} \to 1$. This means that the
supercurrents in the two rings A and B are quantum mechanically
correlated perfectly. It is concluded that not all the quantum
correlations in the two-mode nonclassical state field can be
transferred to the supercurrents; and the transfer depends on the
state of the two-mode nonclassical state field prepared. 相似文献
9.
Structural and thermodynamic properties of wurtzite-type aluminium nitride from first-principles calculations 下载免费PDF全文
The lattice parameter, bulk modulus and its pressure derivative of
the wurtzite-type aluminium nitride (w-AlN) are investigated by using
the Cambridge Serial Total Energy Package (CASTEP) program in the
framework of Density Functional Theory (DFT). The calculated results
are in good agreement
with the available experimental data and other theoretical results.
Through the quasi-harmonic Debye model, the dependences of the
normalized lattice parameters $a/a_{0}$ and $ c/c_{0}$, axial ratio
$c/a$, normalized primitive-cell volume $V/V_{0}$, Debye
temperature ${\it\Theta} _{\rm D} $ and heat capacity $C_{\rm V}$ on
pressure $P $ and temperature $ T$ are obtained. It is found that the
interlayer covalent interactions (Al-N bonds) are more (even a
little) sensitive to temperature and pressure than intralayer ones
(N--N bonds), which gives rise to a little lattice anisotropy in the
w-AlN. 相似文献
10.
Effect of substrate temperature on the growth and properties of boron-doped microcrystalline silicon films 下载免费PDF全文
Highly conductive boron-doped hydrogenated microcrystalline silicon (\mu
c-Si:H) films are prepared by very high frequency plasma enhanced chemical
vapour deposition (VHF PECVD) at the substrate temperatures $T_{\rm S})$
ranging
from 90$^\circ$C to 270$^\circ$C. The effects of $T_{\rm S}$ on the growth and
properties of the films are investigated. Results indicate that the growth
rate, the electrical (dark conductivity, carrier concentration and Hall
mobility) and structural (crystallinity and grain size) properties are all
strongly dependent on $T_{\rm S}$. As $T_{\rm S}$ increases, it is
observed that 1)
the growth rate initially increases and then arrives at a maximum value of
13.3 nm/min at $T_{\rm S}$=210$^\circ$C, 2) the crystalline volume fraction
($X_{\rm c})$ and the grain size increase initially, then reach their maximum
values at $T_{\rm S}$=140$^\circ$C, and finally decrease, 3) the dark
conductivity ($\sigma _{\rm d})$, carrier concentration and Hall mobility have
a similar dependence on $T_{\rm S}$ and arrive at their maximum values at
$T_{\rm S}$=190$^\circ$C. In addition, it is also observed that at a lower
substrate temperature $T_{\rm S}$, a higher dopant concentration is required in
order to obtain a maximum $\sigma _{\rm d}$. 相似文献
11.
Characteristics and parameter extraction for NiGe/n-type Ge Schottky diode with variable annealing temperatures 下载免费PDF全文
Current transport mechanism in Ni-germanide/n-type Ge
Schottky diodes is investigated using current--voltage
characterisation technique with annealing temperatures from 300~\duto 500~\du. Based on the current transport model, a simple method to
extract parameters of the NiGe/Ge diode is presented by using the
$I$--$V$ characteristics. Parameters of NiGe/n-type Ge Schottky
diodes fabricated for testing in this paper are as follows: the
ideality factor $n$, the series resistance $R_{\rm s}$, the
zero-field barrier height $\phi _{\rm b0}$, the interface state
density $D_{\rm it}$, and the interfacial layer capacitance $C_{\rm
i}$. It is found that the ideality factor $n$ of the diode increases
with the increase of annealing temperature. As the temperature
increases, the interface defects from the sputtering damage and the
penetration of metallic states into the Ge energy gap are
passivated, thus improving the junction quality. However, the
undesirable crystallisations of Ni-germanide are observed together
with NiGe at a temperature higher than 400~\du. Depositing a very
thin ($\sim $1~nm) heavily Ge-doped $n^{+}$ Ge intermediate layer
can improve the NiGe film morphology significantly. 相似文献
12.
With a coupling laser locked to caesium 6S$_{1 / 2}$ $F_{\rm
g}$=4--6P$_{3 / 2}$
$F_{\rm e}$=5 cycling transition and a co-propagating probe laser
scanned across
6S$_{1 / 2}$ $F_{\rm g}$=4--6P$_{3 / 2}$ $F_{\rm e}$=3, 4 and 5 transitions, a novel scheme
for sub-Doppler spectra in Doppler-broadened V-type three-level system is
demonstrated by detecting the transmission of the coupling laser through a
caesium vapour cell. The Autler--Townes doublet in the sub-Doppler spectra of the
coupling laser is clearly observed. The effects of coupling laser intensity
on the splitting and linewidth of the Autler--Townes doublet are experimentally
investigated and the results agree well with theoretical predictions. Taking
the multiple hyperfine levels of caesium atom into account, a brief analysis
is presented. 相似文献
13.
In this paper we investigate the gravitational frequency-shift and
deflection of light in the Schwarzschild black hole space-time
surrounded by quintessence. With the analytical and numerical
methods, we find that the gravitational frequency-shift of light in
the Schwarzschild black hole space-time surrounded by the
quintessence increases as the values of the normalization factor $c$
increases, but the gravitational frequency-shift of light decreases
with the quintessential state parameter $ \omega_{\rm q}$
increasing. We also calculate the deflection of light by
quintessence and find that the deflection rate decreases as the
values of the quintessential parameters $c$ and $ \omega_{\rm q}$
increase. 相似文献
14.
In this paper, we have improved the calculation of the relic
gravitational waves (RGW) in two aspects. First, we investigate the
transfer function by taking into consideration the
redshift-suppression effect, the accelerating expansion effect, the
damping effect of free-streaming relativistic particles, and the
damping effect of cosmic phase transition, and give a simple
approximate analytic expression, which clearly illustrates the
dependence on the cosmological parameters. Second, we develop a
numerical method to calculate the primordial power spectrum of RGW in
a very wide frequency range, where the observed constraints on
$n_{\rm s}$ (the scalar spectral index) and $P_{\rm S}(k_0)$ (the
amplitude of primordial scalar spectrum) and the Hamilton--Jacobi
equation are used. This method is applied to two kinds of
inflationary models, which satisfy the current constraints on $n_{\rm
s}$, $\alpha$ (the running of $n_{\rm s}$) and $r$ (the
tensor--scalar ratio). We plot them in the $r-{\it\Omega}_{\rm g}$
diagram, where ${\it\Omega}_{\rm g}$ is the strength of RGW, and
study their measurements from the cosmic microwave background (CMB)
experiments and laser interferometers. 相似文献
15.
Comparative study of different properties of GaN films grown on(0001) sapphire using high and low temperature AlN interlayers 下载免费PDF全文
Comparative study of high and low temperature AlN
interlayers and their roles in the properties of GaN epilayers
prepared by means of metal organic chemical vapour deposition on
(0001) plane sapphire substrates is carried out by high resolution
x-ray diffraction, photoluminescence and Raman spectroscopy. It is
found that the crystalline quality of GaN epilayers is improved
significantly by using the high temperature AlN interlayers, which
prevent the threading dislocations from extending, especially for
the edge type dislocation. The analysis results based on
photoluminescence and Raman measurements demonstrate that there
exist more compressive stress in GaN epilayers with high temperature
AlN interlayers. The band edge emission energy increases from
3.423~eV to 3.438~eV and the frequency of Raman shift of $E_{2
}$(TO) moves from 571.3~cm$^{ - 1}$ to 572.9~cm$^{ - 1}$ when the
temperature of AlN interlayers increases from 700~$^{\circ}$C to
1050~$^{\circ}$C. It is believed that the temperature of AlN
interlayers effectively determines the size, the density and the
coalescence rate of the islands, and the high temperature AlN
interlayers provide large size and low density islands for GaN
epilayer growth and the threading dislocations are bent and
interactive easily. Due to the threading dislocation reduction in
GaN epilayers with high temperature AlN interlayers, the approaches
of strain relaxation reduce drastically, and thus the compressive
stress in GaN epilayers with high temperature AlN interlayers is
high compared with that in GaN epilayers with low temperature AlN
interlayers. 相似文献
16.
A specially designed experiment is performed for investigating gate-induced
drain leakage (GIDL) current in 90nm CMOS technology using lightly-doped
drain (LDD) NMOSFET. This paper shows that the drain bias $V_{\rm D}$ has a
strong effect on GIDL current as compared with the gate bias $V_{\rm G}$ at the
same drain--gate voltage $V_{\rm DG}$. It is found that the difference between
$I_{\rm D}$ in the off-state $I_{\rm D}-V_{\rm G}$ characteristics and the
corresponding one in the off-state $I_{\rm D}-V_{\rm D}$ characteristics, which is
defined as $I_{\rm DIFF}$, versus $V_{\rm DG}$ shows a peak. The difference between
the influences of $V_{\rm D}$ and $V_{\rm G}$ on GIDL current is shown
quantitatively by $I_{\rm DIFF}$, especially in 90nm scale. The difference is
due to different hole tunnellings. Furthermore, the maximum $I_{\rm DIFF
}$($I_{\rm DIFF,MAX})$ varies linearly with $V_{\rm DG}$ in logarithmic coordinates
and also $V_{\rm DG}$ at $I_{\rm DIFF,MAX}$ with $V_{\rm F}$ which is the characteristic
voltage of $I_{\rm DIFF}$. The relations are studied and some related
expressions are given. 相似文献
17.
A simulation study of microstructure evolution during solidification process of liquid metal Ni 下载免费PDF全文
A molecular dynamics simulation study has been performed for the
microstructure evolution in a liquid metal Ni system during
crystallization process at two cooling rates by adopting the
embedded atom method (EAM) model potential. The bond-type index
method of Honeycutt--Andersen (HA) and a new cluster-type index
method (CTIM-2) have been used to detect and analyse the
microstructures in this system. It is demonstrated that the cooling
rate plays a critical role in the microstructure evolution: below the
crystallization temperature $T_{\rm c}$, the effects of cooling rate
are very remarkable and can be fully displayed. At different cooling
rates of $2.0\times10^{13}$\,K\,$\cdot$\,s$^{-1}$ and
$1.0\times10^{12}$\,K\,$\cdot$\,s$^{-1}$, two different kinds of
crystal structures are obtained in the system. The first one is the
coexistence of the hcp (expressed by (12 0 0 0 6 6) in CTIM-2) and
the fcc (12 0 0 0 12 0) basic clusters consisting of 1421 and 1422
bond-types, and the hcp basic cluster becomes the dominant one with
decreasing temperature, the second one is mainly the fcc (12 0 0 0 12
0) basic clusters consisting of 1421 bond-type, and their
crystallization temperatures $T_{\rm c}$ would be 1073 and 1173\,K,
respectively. 相似文献
18.
Scaling of anisotropic flows and nuclear equation of state in intermediate energy heavy ion collisions 下载免费PDF全文
Elliptic flow ($v_2$) and hexadecupole flow ($v_4$) of light
clusters have been studied in detail for 25 MeV/nucleon $^{86}$Kr
+ $^{124}$Sn at large impact parameters by using a quantum
molecular dynamics model with different potential parameters. Four
sets of parameters including soft or hard equation of state (EOS)
with or without symmetry energy term are used. Both
number-of-nucleon ($A$) scaling of the elliptic flow versus
transverse momentum ($p_{\rm t}$) and the scaling of $v_4/A^{2}$ versus
$(p_{\rm t}/A)^2$ have been demonstrated for the light clusters in all
above calculation conditions. It is also found that the ratio of
$v_4/{v_2}^2$ maintains a constant of 1/2 which is independent of
$p_{\rm t}$ for all the light fragments. Comparisons among different
combinations of the EOS and the symmetry potential term show that
the above scaling behaviours are sound and independent of the
details of potential, while the strengths of flows are sensitive
to the EOS and the symmetry potential term. 相似文献
19.
This paper employs the highly accurate valence internally contracted multireference configuration interaction method to investigate the potential energy curves (PECs) for the ground state (X 1 Σ +) and two low-lying excited states (A 1 Π and D 1 of phosphorus nitride (PN) radical with the correlation-consistent basis set,aug-cc-pV6Z,in the valence range.Relativistic effects are considered in these calculations.The spectroscopic constants of the X 1 Σ + and A 1 Π states are calculated based on the PECs,and the results are in good accord with the available experimental data.The first 30 vibrational states for the X 1 Σ + state and the first 40 vibrational states for theA 1 Π state are determined when J=0.For each vibrational state,molecular constants G(υ),B(υ) and D(υ) are also attained. 相似文献
20.
In the framework of density functional theory, using the plane-wave
pseudopotential method, the nitrogen vacancy ($V_{\rm N})$ in both
wurtzite and zinc-blende AlN is studied by the supercell approach.
The atom configuration, density of states, and formation energies of
various charge states are calculated. Two defect states are
introduced by the defect, which are a doubly occupied single state
above the valance band maximum (VBM) and a singly occupied triple
state below the conduction band minimum (CBM) for wurtzite AlN and
above the CBM for zinc-blende AlN. So $V_{\rm N}$ acts as a deep
donor in wurtzite AlN and a shallow donor in zinc-blende AlN. A
thermodynamic transition level $E({3 + } \mathord{\left/ {\vphantom
{{3 + } + }} \right. \kern-\nulldelimiterspace} + )$ with very low
formation energy appears at 0.7 and 0.6eV above the VBM in wurtzite
and zinc-blende structure respectively, which may have a wide shift
to the low energy side if atoms surrounding the defect are not fully
relaxed. Several other transition levels appear in the upper part of
the bandgap. The number of these levels decreases with the structure
relaxation. However, these levels are unimportant to AlN properties
because of their high formation energy. 相似文献