Under various uniaxial stresses,both strains with low symmetry and isotropic strains of crystals take place.The former fives the strain-induced low-symmetry crystal fields and accordingly splittings of levels;the latter gives the isotropic parts of strain-induced crystal fields and accordingly shifts of levels.By using the wavefunctions obtained from the diagonalization of the complete d^3 energy matrix in a regular octahedral field,the relevant matrix elements and accordingly strain-induced splittings and/or shifts of t2^32E and t2^34A2 for MgO:Cr^3+ have been calculated.Their physical origins have been thoroughly analyzed and revealed.It is the admixtures of basic wavefunctions resulted from the spinorbit interaction and/ork Coulomb interaction and/or Kramers degeneracy that make strain-induced splittings of levels nonzero.In contrast with this,strain-induced shifts come mainly from the zero-order approximate wavefunctions.It is found that there are nonvanishing matrix elements of operators T2ξ,T2η and T2ζ between wavefunctions with positive Ms and those with negative ms',which have important effects on strain-induced splittings of levels.The shifts of t2^32E under both hydrostatic pressure and uniaxial pressure have been uniformly calculated.The important results of Yc,Zc,Pc,Qc and have been evaluated.
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