Effect of cation arrangement on the electronic structures of the perovskite solid solutions <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow><mo>(</mo><mi>SrTiO</mi></mrow><mn>3</mn></msub><mo>)</mo><msub><mrow></mrow><mrow><mn>1</mn><mo>−</mo><mi>x</mi></mrow></msub><msub><mrow><mo>(</mo><mi>LaCrO</mi></mrow><mn>3</mn></msub><mo>)</mo></math></span><i><span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML"><msub><mrow></mrow><mi>x</mi></msub></math></span></i> from first principles