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Variational Quantum Monte Carlo Ground State of Lithium |
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Many-particle effects are difficult to determine within the
usual one-particle picture. But due to the high dimensionality,
many-particle calculations have been hardly possible in the past.
As one of the first many-particle computations for the
Schrödinger equation in solid state physics
we show results from caluclations in which we considered
up to 162 electrons.
 Fig. 1: Total energy vs. lattice constant of the lithium solid; 1s states are atomic orbitals of Slater type, 2s states are plane waves (upper curve,triangles) and LCAO wave functions (lower curve, diamonds).
The ground state of bulk lithium at zero temperature is simulated by the
variational quantum Monte Carlo (VQMC) algorithm. This rather simple
stochastic procedure yields the total energy of the ground state, the
lattice constant, and the bulk modulus quite near to the experimental values.
The total energy and its
constituents are determined for two parametrized sets of trial wave
functions as shown in Fig. 1. Including correlation by a Jastrow
factor the one-determinant
ansatz consists of either plane waves or a linear combination of Slater
orbitals for the Li 2s states. The latter yields the best results.
See also:
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1994
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