All Systems in Population Failed Relaxation Error

[Rahim Zaman]

I am trying to use USPEX to predict the structure of an experimentally refined tetragonal unit cell using a fixed cell. I used the attached input.uspex file, but got the error: “AssertionError: All systems in population failed relaxation.” I am wondering what this error means and what could be going wrong with my calculation, as this is an experimentally known crystal structure. Any replies are appreciated!

{
    optimizer: {
        type: GlobalOptimizer
        target: {
            type: Atomistic
            compositionSpace: {symbols: [X Y Z]
                               blocks: [[1 1 4]]}
            cellUtility: {cellParameters: {a: 6.9 b: 6.9 c: 6.0 alpha: 90.0 beta: 90.0 gamma: 90.0}}
            randSym: {nsym: '75-142'}
        }
        optType: enthalpy
        selection: {
            type: USPEXClassic
            popSize: 40
            bestFrac: 0.6
            optType: (aging enthalpy)
            fractions: {
                heredity: (0.4 0.7 0.5)
                softmodemutation: (0.2 0.5 0.2)
                randSym: (0.05 0.5 0.1)
                randTop: (0.05 0.5 0.1)
                permutation: (0.05 0.3 0.1)
            }
        }
    }
    stages: [vasp1 vasp2 vasp3 vasp4 vasp5]
    numParallelCalcs: 20
    numGenerations: 50
    stopCrit: 30
}