123 research outputs found
Electron attachment to valence-excited CO
The possibility of electron attachment to the valence state of CO
is examined using an {\it ab initio} bound-state multireference configuration
interaction approach. The resulting resonance has symmetry;
the higher vibrational levels of this resonance state coincide with, or are
nearly coincident with, levels of the parent state. Collisional
relaxation to the lowest vibrational levels in hot plasma situations might
yield the possibility of a long-lived CO state.Comment: Revtex file + postscript file for one figur
Towards the electron EDM search. Theoretical study of PbF
We report ab initio relativistic correlation calculations of potential curves
and spectroscopic constants for four lowest-lying electronic states of the lead
monofluoride. We also calculated parameters of the spin-rotational Hamiltonian
for the ground and the first excited states including P,T-odd and P-odd terms.
In particular, we have obtained hyperfine constants of the Pb nucleus.
For the state MHz, MHz and for
the A MHz, MHz. Our values of
the ground state hyperfine constants are in good agreement with the previous
theoretical studies. We discuss and explain seeming disagreement in the sign of
the constant with the recent experimental data. The effective
electric field on the electron , which is important for the planned
experiment to search for the electric dipole moment of the electron, is found
to be 3.3 * 10^{10} V/cm
Towards the electron EDM search: Theoretical study of HfF+
We report first ab initio relativistic correlation calculations of potential
curves for ten low-lying electronic states, effective electric field on the
electron and hyperfine constants for the ^3\Delta_1 state of cation of a heavy
transition metal fluoride, HfF^+, that is suggested to be used as the working
state in experiments to search for the electric dipole moment of the electron.
It is shown that HfF^+ has deeply bound ^1\Sigma^+ ground state, its
dissociation energy is D_e=6.4 eV. The ^3\Delta_1 state is obtained to be the
relatively long-lived first excited state lying about 0.2 eV higher. The
calculated effective electric field E_eff=W_d|\Omega| acting on an electron in
this state is 5.84*10^{24}Hz/(e*cm)Comment: 4 page
Configuration interaction calculation of hyperfine and P,T-odd constants on ^{207}PbO excited states for the electron EDM experiments
We report first configuration interaction calculations of hyperfine constants
A_\parallel and the effective electric field W_d acting on the electric dipole
moment of the electron, in two excited electronic states of ^{207}PbO. The
obtained hyperfine constants, A_\parallel = -3826 MHz for the a(1) state and
A_\parallel = 4887 MHz for the B(1) state, are in very good agreement with the
experimental data, -4113 MHz and 5000 \pm 200 MHz, respectively. We find W_d =
-(6.1 ^{+1.8}_{-0.6}) 10^{24} Hz/(e cm) for a(1), and W_d = (8.0 \pm 1.6)
10^{24} Hz/(e cm) for B(1). The obtained values are analyzed and compared to
recent relativistic coupled cluster results and a semiempirical estimate of W_d
for the a(1) state.Comment: 6 pages, REVTeX4 style, submitted to Pthys.Rev.
Variational Hilbert space truncation approach to quantum Heisenberg antiferromagnets on frustrated clusters
We study the spin- Heisenberg antiferromagnet on a series of
finite-size clusters with features inspired by the fullerenes. Frustration due
to the presence of pentagonal rings makes such structures challenging in the
context of quantum Monte-Carlo methods. We use an exact diagonalization
approach combined with a truncation method in which only the most important
basis states of the Hilbert space are retained. We describe an efficient
variational method for finding an optimal truncation of a given size which
minimizes the error in the ground state energy. Ground state energies and
spin-spin correlations are obtained for clusters with up to thirty-two sites
without the need to restrict the symmetry of the structures. The results are
compared to full-space calculations and to unfrustrated structures based on the
honeycomb lattice.Comment: 22 pages and 12 Postscript figure
Theory of excited state absorptions in phenylene-based -conjugated polymers
Within a rigid-band correlated electron model for oligomers of
poly-(paraphenylene) (PPP) and poly-(paraphenylenevinylene) (PPV), we show that
there exist two fundamentally different classes of two-photon A states in
these systems to which photoinduced absorption (PA) can occur. At relatively
lower energies there occur A states which are superpositions of one
electron - one hole (1e--1h) and two electron -- two hole (2e--2h) excitations,
that are both comprised of the highest delocalized valence band and the lowest
delocalized conduction band states only. The dominant PA is to one specific
member of this class of states (the mA). In addition to the above class of
A states, PA can also occur to a higher energy kA state whose 2e--2h
component is {\em different} and has significant contributions from excitations
involving both delocalized and localized bands. Our calculated scaled energies
of the mA and the kA agree reasonably well to the experimentally
observed low and high energy PAs in PPV. The calculated relative intensities of
the two PAs are also in qualitative agreement with experiment. In the case of
ladder-type PPP and its oligomers, we predict from our theoretical work a new
intense PA at an energy considerably lower than the region where PA have been
observed currently. Based on earlier work that showed that efficient
charge--carrier generation occurs upon excitation to odd--parity states that
involve both delocalized and localized bands, we speculate that it is the
characteristic electronic nature of the kA that leads to charge generation
subsequent to excitation to this state, as found experimentally.Comment: Revtex4 style, 2 figures inserted in the text, three tables, 10 page
Cyclic Versus Linear Isomers Produced by Reaction of the Methylidyne Radical (CH) with Small Unsaturated Hydrocarbons
Dissociation dynamics of diatomic molecules in intense laser fields: a scheme for the selection of relevant adiabatic potential curves
We investigated the nuclear dynamics of diatomic molecular ions in intense laser fields by analyzing their fragment kinetic-energy release (KER) spectra as a function of the pump-probe delay τ . Within the Born-Oppenheimer (BO) approximation, we calculated ab initio adiabatic potential-energy curves and their electric dipole couplings, using the quantum chemistry code GAMESS. By comparing simulated KER spectra as a function of either τ or the vibrational quantum-beat frequency for the nuclear dynamics on both individual and dipole-coupled BO potential curves with measured spectra, we developed a scheme for identifying electronic states that are relevant for the dissociation dynamics. We applied this scheme to investigate the nuclear dynamics in O[subscript 2][superscript +] ions that are produced by ionization of neutral O[subscript 2] molecules in an ultrashort infrared (IR) pump pulse and dissociate due to the dipole coupling of molecular potential curves in a delayed IR probe laser field
- …