Setting the default value to taxonomy column in sharepoint 2010 using client object model

            ClientContext clientContext = new ClientContext(siteUrl);

            Web site = clientContext.Web;

            List list = site.Lists.GetByTitle("LibraryName");

            FieldCollection collField = list.Fields;

            string fieldSchema = "<Field Type='TaxonomyFieldType' DisplayName='SoftwareColumn' Name='SoftwareColumn' />";

            collField.AddFieldAsXml(fieldSchema, true, AddFieldOptions.DefaultValue);

            //oneField.DefaultValue = "ASP.NET|4c984b91-b308-4884-b1f1-aee5d7ed58b2"; // wssId[0].ToString() + ";#" + term.Name + "|" + term.Id.ToString().ToLower();

            clientContext.Load(collField);           

            clientContext.ExecuteQuery();