Liquid crystal compound, liquid crystal composition thereof, and liquid crystal display device

A liquid crystal compound of general formula F:

• wherein,
• RF1 represents —H, halogen, C1-12 linear alkyl or C3-12 branched alkyl,
• wherein one or more nonadjacent —CH2— in the C1-12 linear alkyl or the C3-12 branched alkyl can each be independently replaced by —C≡C—, —O—, —CO—, —CO—O— or —O—CO—, and one or more —H in the C1-12 linear alkyl or the C3-12 branched alkyl can each be independently substituted by —F or —Cl;
• ring
• and ring
• each independently represents
• wherein one or more —CH2— in
• can be replaced by —O—, one or more single bond in the rings can be replaced by double bond, wherein one or more —H on
• can each be independently substituted by —CN, —F or —Cl, and one or more —CH═ in the rings can be replaced by —N═;
• XF represents —O—, —S— or —CO—;
• LF1 and LF2 each independently represents —H, —F, —Cl, —CF3 or —OCF3;
• ZF1 and ZF2 each independently represents single bond, —CO—O—, —O—CO—, —CH2O—, —OCH2—, —CH═CH—, —C≡C—, —CH2CH2—, —CF2CF2—, —(CH2)4—, —CF2O— or —OCF2—;
• nF1 and nF2 each independently represents 0, 1 or 2, wherein, when nF1 represents 2, ring
• can be the same or different, wherein when nF2 represents 2, ring
• can be the same or different, and ZF2 can be the same or different;
• and
• nF3 represents an integer of 0-4.