I have solved this using this code. i used pickerposition: "top-left".
$(".form_datetime").datetimepicker({
//language: 'fr',
format: 'dd/mm/yyyy - hh:ii',
weekStart: 1,
todayBtn: 1,
autoclose: 1,
todayHighlight: 1,
startView: 2,
forceParse: 0,
showMeridian: 0,
minuteStep: 1,
pickerPosition: "top-left",
container: '#divmodalcontent',
widgetPositioning: {
vertical: 'auto',
horizontal: 'auto'
}
}).on('changeDate', function (ev) {
$('#followupdetmodal').bootstrapValidator('revalidateField', $('#txtdatetimedisplay_' + $(this).attr("data-link-field")));
});