Dear all:
I try to calculate the band gap of BaTe using hybrid potentials of B3PW91, B3LYP and PBEH in libxc. But I could not get the appropriate band gap of BaTe. The experimental gap of BaTe in B1 structure is 3.4 eV. The LDA band gap is 1.58 eV using LSDAPerdew-Wang potential. However, I get 1.05 eV (B3PW91), 1.3 eV (B3LYP), and 1.04 eV (PBEH).
Could you give me some advice?

My input file is:
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet href="http://xml.exciting-code.org/inputfileconverter/inputtohtml.xsl" type="text/xsl"?>
<input xsi:noNamespaceSchemaLocation="http://static.exciting-code.org/hydrogen/excitinginput.xsd"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<title>BaTe</title>
<structure speciespath="/share/data1/lvty/tool/exciting/exciting/species/">
<crystal scale="13.23">
<basevect>0.0 0.5 0.5</basevect>
<basevect>0.5 0.0 0.5</basevect>
<basevect>0.5 0.5 0.0</basevect>
</crystal>
<species speciesfile="Ba.xml">
<atom coord="0.0000 0.0000 0.0000" bfcmt="0.0 0.0 0.0" />
</species>
<species speciesfile="Te.xml">
<atom coord="0.5000 0.5000 0.5000" bfcmt="0.0 0.0 0.0" />
</species>
</structure>
<groundstate
ngridk="10 10 10"
rgkmax="10.0"
gmaxvr="40"
epsengy="1.0d-6"
epspot="1.0d-6"
nempty="5"
maxscl="50">
<libxc xc="XC_HYB_GGA_XC_PBEH"/>
</groundstate>
<properties>
<bandstructure character="true">
<plot1d>
<path steps="10">
<point coord="0.00000 0.00000 0.00000" label="GAMMA" />
<point coord="0.50000 0.00000 0.50000" label="X" />
</path>
</plot1d>
</bandstructure>
</properties>
</input>