spin-symmetry broken ground-state of uo2 in dft+u approach: the smc method

It turns out that the ground states of some systems are symmetry-broken states in which some property is not symmetrically distributed. in the case of strongly correlated electron systems that were studied by the dft+u method, researchers have shown that the total energy of the system is a multi-minima function of electron-configuration parameters and one has to single out the ground state out of the couples of minimum-energy states. however, the methods already introduced to determine these local minimum states, were not able to predict all such states, which may include the &true& ground state. in this work, we introduce a new simple and straight-forward method of smc to find the gs as well as the meta-stable states of the 1k-order anti-ferromagnetic configuration for uo2. using this method, it is shown that the ground state of the uo2 system is a spin-symmetry broken state of the electron spin magnetizations of oxygen atoms. depending on the way we apply the smc method, we obtain different numbers of meta-stable states, but the same ground states. the energetic properties, geometric properties, the electronic density distributions, and the electronic polarization density distributions of the ground state and the meta-stable states are shown to be different from each other. these properties also are shown to be sensitive to the magnitude of the initial opposite magnetizations of up-spin u-atoms (u1) and down-spin u-atoms (u2) in the 1k-order anti-ferromagnetic configuration, but the number of meta-stable states as well as the ground-state properties are insensitive to this magnitude. using the pbesol-gga approximation for the exchange-correlation, we obtain the ground-state properties in excellent agreement with experiments.

spin-symmetry broken ground-state of uo2 in dft+u approach: the smc method

it turns out that the ground states of some systems are symmetry-broken states in which some property is not symmetrically distributed. in the case of strongly correlated electron systems that were studied by the dft+u method, researchers have shown that the total energy of the system is a multi-minima function of electron-configuration parameters and one has to single out the ground state out of the couples of minimum-energy states. however, the methods already introduced to determine these local minimum states, were not able to predict all such states, which may include the &true& ground state. in this work, we introduce a new simple and straight-forward method of smc to find the gs as well as the meta-stable states of the 1k-order anti-ferromagnetic configuration for uo2. using this method, it is shown that the ground state of the uo2 system is a spin-symmetry broken state of the electron spin magnetizations of oxygen atoms. depending on the way we apply the smc method, we obtain different numbers of meta-stable states, but the same ground states. the energetic properties, geometric properties, the electronic density distributions, and the electronic polarization density distributions of the ground state and the meta-stable states are shown to be different from each other. these properties also are shown to be sensitive to the magnitude of the initial opposite magnetizations of up-spin u-atoms (u1) and down-spin u-atoms (u2) in the 1k-order anti-ferromagnetic configuration, but the number of meta-stable states as well as the ground-state properties are insensitive to this magnitude. using the pbesol-gga approximation for the exchange-correlation, we obtain the ground-state properties in excellent agreement with experiments.